KAKTLR is defective for promoting motility in T47D cells. T47D/tva cells were infected with empty RCAS A (mock) or RCAS A vectors engineered to express wild-type FAK or KAKTLR. (A) Control cells (lanes 1 to 3) or FAK (lanes 4 to 6)- or KAKTLR (lanes 7 to 9)-expressing cells growing in culture (lanes 1, 4, and 7), held in suspension (lanes 2, 5, and 8) or plated onto collagen for 45 min (lanes 3, 6, and 9) were lysed, and phosphorylation of FAK at tyrosine 397 was examined by Western blotting with PY397 (top). The blot was stripped and reprobed with BC4 as a loading control (bottom). (B) T47D/tva cells infected with empty RCAS A or expressing FAK or KAKTLR were assessed for haptotactic motility in response to collagen I. The average fold change in motility for nine experiments, each performed in triplicate, is shown. Error bars denote standard errors. *, the difference in motility between FAK- and mock-expressing cells was statistically significant (P < 0.05). The difference in motility between KAKTLR- and mock-expressing cells was not statistically significant.