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MEKK2, a member of the MAP3K family, plays a pivotal role in signaling cascades that regulate cellular responses such as proliferation, differentiation, and stress adaptation. Here the authors determine the crystal structure of the kinase domain of MEKK. Using a structure-directed approach they deconvolute the molecular basis of its autophosphorylation and its recruitment and phosphorylation of MAP2Ks, MEK5 and MKK6.

The validation and analysis of X-ray crystallographic data is essential for reproducibility and the development of crystallographic methods. Here, the authors describe a repository for crystallographic datasets and demonstrate some of the ways it could serve the crystallographic community.

LIM domain kinases are key regulators of cofilin and consequently actin severing. Here, the authors show that the LIMK PDZ domain is important for autoregulation using a conserved surface distal to the canonical PDZ-binding cleft.

The protein kinase MEKK3 interacts with CCM2, which is associated with the predominantly cerebrovascular CCM disease. Here the authors use structural, biochemical, cell biology and in vivotechniques to show that regulation of Rho signalling by the CCM2:MEKK3 complex is needed to maintain neurovascular integrity.

A growing number of ‘pseudoenzymes’ with a regulatory role in signal transduction processes but without catalytic activity are being identified. Here, the authors identify two pseudoGTPase domains in p190RhoGAP, characterize them biochemically and structurally and show that they influence RhoGAP activity.

Arginine protein kinases regulate bacterial signaling cascades through phosphorylation of key arginine residues. Crystal structures of the kinase McsB provide the first glimpse of how these unusual enzymes recognize their protein substrates and are allosterically regulated.

Here the authors screen a saturation mutagenesis library of the disordered N-terminal tail of the actin severing protein cofilin. Their results reveal how a key phosphorylation site can balance competing sequence constraints on function and regulation.

Vein of Galen malformations (VOGMs) are severe congenital brain arteriovenous malformations. Here the authors work to elucidate the pathogenesis of VOGMs by performing an integrated analysis of 310 VOGM proband family exomes and 336,326 human cerebrovasculature single-cell transcriptomes to identify mutations of key signaling regulators.

Glucocorticoid receptor (GR) agonists - used in the treatment of solid malignant tumors to reduce inflammation - could potentially affect the anti-tumor activity of chemotherapy. Here, the authors identify a mechanism of cisplatin resistance observed with GR agonist treatment, and show the binding and activation of GR by cisplatin, which leads to MAST1 activation and subsequent MAPK re-activation.

Inhibition of DLC1 RhoGAP by p120RasGAP allows for crosstalk between the Rho and Ras pathways. Here, Chau et al. present the co-crystal structure of DLC1 RhoGAP domain and p120RasGAP SH3 domain and probe the interaction with biochemical studies.

Tumour cells may undergo a dramatic metabolic shift in which glycolysis is favoured despite the presence of oxygen. By solving its crystal structure, Hitosugi et al. reveal how phosphorylation of the enzyme phosphoglycerate mutase 1 regulates glycolytic flux in cancer cells.

Chen and colleagues report that the third enzyme in the oxidative pentose phosphate pathway (PPP), 6PGD, controls cancer cell proliferation by regulating LKB1–AMPK signalling. Inhibitors of 6PGD decrease tumorigenesis in mouse xenografts.

Tousled-like kinase 2 (TLK2) phosphorylates ASF1 histone chaperones to promote nucleosome assembly in S phase. Here, the authors show that TLK2 targets ASF1 by simulating its client protein histone H3, exploiting a primordial protein interaction surface for regulatory control.

Richard Lifton and colleagues report a genomic analysis of cutaneous T cell lymphoma (CTCL). Their results implicate several pathways in CTCL pathogenesis, including genes involved in T cell activation and apoptosis, NF-κB signaling, chromatin remodeling and DNA damage response.

Ruth Halaban and colleagues report exome sequences of 147 melanoma tumors. They identified a recurrent somatic activating alteration in the Rho GTPase RAC1 in sun-exposed melanomas.

Trever Bivona and colleagues identify the upregulation of the AXL kinase in human non–small cell lung cancer with acquired resistance to erlotinib. Inhibition of AXL restores sensitivity to erlotinib in in vitro and in vivo tumor models. The authors suggest AXL as a potential therapeutic target that may prevent or overcome acquired resistance in patients with EGFR-mutant lung cancer.

Crystal structures of integrin β5 tails with PAK4 reveal a unique interaction in which integrin β5 is not phosphorylated by PAK4 but rather inhibits PAK4 activity.

Richard Lifton, Barbara Kazmierczak and colleagues report the identification of a new enterocolitic and autoinflammatory syndrome, which they find is caused by de novo gain-of-function mutations affecting the inflammasome protein NLRC4. Cells with mutant NLRC4 produce elevated levels of cleaved caspase-1, which leads to cell death by pyroptosis.