ROR1P(841)A fails to associate with cortactin, induce phosphorylation of cortactin, or enhance migration of MCF7 cells. a Schematic depicts the structure of ROR1 protein with different domains. b ΔPRD represents the truncated form of ROR1 without its proline-rich region (PRD). c Amino acid sequences of the PRD of ROR1. Asterisks indicate the proline (P) residues that were replaced with alanine (A). d Immunoblots of anti-ROR1 i.p. by using lysates of MCF7 (Ctrl), MCF7–WT ROR1, or MCF7 cells transfected with ROR1–ΔPRD, as indicated on the top, and probed with antibodies specific for ROR1 or cortactin, as indicated on the left. An immunoblot of the WCL probed with anti-cortactin mAb is in the bottom panel. e Immunoblots of anti-ROR1 i.p. by using lysates of MCF7-Ctrl, MCF7–ΔPRD, MCF7–WT ROR1, or MCF7 transfected with each of the various mutated forms of ROR1, as indicated on the top, and probed with antibodies specific for ROR1, cortactin, or ARHGEF1, as indicated on the left. An immunoblot of the WCL probed with anti-cortactin is in the bottom panel. f Immunoblots of lysates prepared from serum-starved MCF7 (Ctrl), MCF7–ΔPRD, MCF7–WT ROR1, or MCF7 cells transfected with each of the various mutated forms of ROR1, as indicated on top, which subsequently were treated without (−) or with (+) Wnt5a (100 ng/ml), as indicated on the top; the membranes were probed with antibodies specific for ROR1, Cortactin, or pCortactin, as indicated on the left. g Immunoblot of activated RhoA (RhoA–GTP, top panel) or total RhoA (RhoA total, bottom panel) found in lysates of MCF7 (Ctrl), MCF7–ΔPRD, MCF7–WT ROR1, or MCF7 expressing any one of the various mutant forms of ROR1, as indicated on top of each lane in Fig. 1f. h Columns indicate the mean number of migrated cells at 10 h of MCF7 (Ctrl), MCF7–ΔPRD, MCF7 expressing any one of the various mutant forms of ROR1, or MCF7–WT ROR1, as indicated below, which were serum-starved and then examined for migration without (−) or with (+) Wnt5a (200 ng/ml), as indicated at the bottom. Data are shown from three independent experiments (P < 0.05; P < 0.01, as calculated by one-way ANOVA with Bonferroni’s multiple-comparison test).