The SCF ubiquitin ligase complex is involved in actin regulation. For all grayscale panels, staining is for F-actin. RBX1 and roc1a phenocopy the SCAR complex in human (A, top row) and fly (A, bottom row) cells. Bar, 50 µm. (B) Depletion of various SCF members phenocopies SCAR knockdown in fly cells. Bar, 20 µm. (C) roc1a/RBX1 depletion does not affect SCAR complex stability as measured by Sra1 or WASF2 protein levels in Western blot, respectively in fly cells (top) or human cells (bottom left), in the same situation when depleting other SCAR complex members does. Equal loading is indicated by tubulin staining of the same gels. The RBX1 knockdown in parallel cultures causes significant depletion (bottom right), with loading shown by staining for CDC2. (D) RacV12 overexpression (as marked by GFP, green; F-actin is red in top panels and grayscale in the bottom; blue is DAPI) rescues spiky phenotype of roc1a and slmb but not that of scar. Bar, 50 µm. (E) RacV12 overexpression (as marked by myc-tag, green; same staining for rest as in D) rescues RBX1 knockdown but not that of NCKAP1. Bar, 50 µm.