DDR2 and lung carcinoma: Co-activation of MET, AXL, ERBB2, and EPHA2 (Figure 4), and co-activation of DDR1 with EGFR (Figure 3B), DDR2, HCK, PDGFRA, and FGR (Figure 6) is evidence that simultaneous activation of multiple tyrosine kinases may be common in lung cancer.