SRC and malignant colon neoplasm: We also found that tyrosine phosphorylation of paxillin, a focal adhesion protein that is a substrate of c-Src in colon cancer cells (Rodina et al, 1999), was elevated in the metastatic cell lines (shown for KM12L4A in Figure 1B), implying that the additional c-Src protein was active at peripheral sites.