Fig. 6: SRPK1 is an important downstream mediator of LIMK2.

a Schematic representation of SRPK1 protein with its identified phosphorylation sites. b MDA-MB-231 cells were treated with either LX7101 (5 μM) or vehicle control for 6 h. SRPK1 was immunoprecipitated from LX7101- and vehicle-treated-MDA-MB-231 cells. Immunoprecipitates were analyzed by immunoblotting with pan-phospho serine antibodies and beta-actin antibodies (loading control). c MDA-MB-231 cells were treated with LX7101 (5 μM), SRPK1 inhibitor SRPIN340 (10 μM), or vehicle control for 6 h. Expression of the indicated proteins was measured by immunoblotting. Beta-actin was used as a loading control. d LIMK2 in vitro kinase assays were performed in the presence and absence of ATP (1 mM). The samples were analyzed by immunoblotting for serine phosphorylation and total SRPK1. e TNBC cell lines (MDA-MB-231 and BT-549) expressing SRPK1 shRNA were analyzed using a 3D spheroid invasion assay. Representative images taken at the indicated times are shown. Scale bar, 250 µm. f Relative invasion (%) calculated from the data presented in e. g Extracellular matrix degradation capacity of TNBC cell lines (MDA-MB-231 and BT-549) expressing SRPK1 shRNA was analyzed using a gelatin degradation assay. Cells were stained with phalloidin (red) and DAPI (blue). Gelatin (green) degradation appears as black areas. Representative images are shown. Scale bar, 500 µm. Data are represented as the means ± SD. ***P < 0.001; ****P < 0.0001.