TRPC7 is associated with syndecan-4 and focal adhesions. (A) Immunostaining of wt, s4ko, s1ko, and s1S4 double KO MEFs shows colocalization of TRPC7 with paxillin at focal adhesions (arrowheads). Fewer focal adhesions and stress fibers were noted in s4ko and s1s4ko MEFs. (B and C) Syndecan-4 clustering on wt MEF cell surfaces with core protein–directed antibody followed by cell lysis and Western blotting shows copurifying TRPC7 and α-actinin, a known binding partner of syndecan-4, but not p120 catenin. Confocal microscopy with line scanning of wt MEF cells shows coalignment of TRPC7 and α-actinin. The data shown are from a single representative cell out of three experiments. (D) Silencing TRPC7, but not TRPC1, gene expression results in a reduction of calcium in s4ko MEFs. n = 20 for control and TRPC1 siRNA and n = 72 for TRPC7 siRNA. (E and F) Knockdown of TRPC7 in s4ko MEFs increases stress fibers containing αSMA. n > 100 cells per condition in F. Data are mean ± SEM. ***, P < 0.001; **, P < 0.01; unpaired t test.