The N-terminal SH3 domain of CrkL plays a critical role in enhancement of cell adhesion. (A) Schematic representation of CrkL and its mutants. (B) Transient expression of CrkL and its mutants with C3G in COS7 cells. Expression plasmids for wild type and various mutants of CrkL, as indicated, were transfected with that of C3G into COS7 cells. Cells were harvested 2 days after transfection, and total cell lysates (TCL) and anti-C3G immunoprecipitates were subjected to anti-CrkL immunoblotting followed by reprobing with anti-C3G. (C) Effects of transiently expressed CrkL mutants on adhesion of 32D/EpoR-Wt cells to fibronectin. The expression plasmids for wild type and various mutants of CrkL, as indicated, were transfected into 32D/EpoR-Wt cells along with pRL-SV. Transiently transfected cells were subjected to the cell adhesion assay as described in Materials and Methods. (D) Dose-dependent effects of the CrkL dSH3N and dSH2 mutants on 32D/EpoR-Wt cell adhesion to fibronectin. 32D/EpoR-Wt cells were transfected with indicated amounts (microgram) of the expression plasmids for dSH3N and dSH2 mutants of CrkL or the pSG5 vector plasmid and subjected to the cell adhesion assay.