Using a TGFR kinase inhibitor, SB431542 (SB), we found that SB down-regulates the phosphorylation of FAK by approximately 25% in A549 and CL1-5 cells (Fig. 7D), indicating that TGFR kinase activity may be related to the phosphorylation of FAK in lung cancer cells. Here, PTK2 is linked to lung cancer.