Figure 2: Crabp1-ERK1/2 activation by compounds 3 and 4 stimulates PP2A in ESC. | Scientific Reports

Figure 2: Crabp1-ERK1/2 activation by compounds 3 and 4 stimulates PP2A in ESC.

From: All trans-retinoic acid analogs promote cancer cell apoptosis through non-genomic Crabp1 mediating ERK1/2 phosphorylation

Figure 2

(A) ERK activation elicited by RA and compounds 3 and 4 for 30 min is abolished in Crabp1 KO ESC. (B) Semi-in vitro kinase assay. Partially immuno-purified Crabp1 complex (bottom) activates recombinant ERK1/2 in vitro under 100 nM RA, C3, and C4 treatment for 30 min. (C) RA and Compound 3 decrease cell viability as detected by MTT assay with 100 nM treatments for 24 hrs. (D) G1 phase expansion by RA and compounds 3 and 4 in WT ESC but not in Crabp1 KO ESC. Cells were treated with RA and compounds 3 and 4 at 100 nM for 12 hrs before flow cytometric analysis. Asterisk shows significance: RA (p = 0.05), C3 (p = 0.05) and C4 (p = 0.04) versus control, and mean ± S.E.M (n = 4). (E) WT ESCs were transfected with scrambled (control) and siCrabp1 (Crabp1 KD) followed by RA treatment (100 nM). RA-induced phosphatase activity (detected for free phosphate) is blocked by Crabp1 knockdown. Asterisk shows significance: 30min (p = 0.01), 3hr (p = 0.002), and 6hr (p = 0.004) versus WT ESC (left). RA-stimulated PP2A activation is blocked by ERK1/2 inhibitor, FR180204; 3 hr (p = 0.03) versus vehicle (center). RA, compounds 3 and 4 stimulate PP2A activity after 100 nM treatment for 3 hrs in WT ESC but not in Crabp1 KO ESC. RA (p < 0.001), C3 (p = 0.017), and C4 (p = 0.001) versus control (right). Data (A–E) are representative of at least 3 independent experiments.

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