NTRK1 and cancer: Thus, our data suggest that the upregulation of the FGF2-FGFR1 pathway in EGFR mutation-positive lung cancer cells does not always confer resistance to gefitinib; conversely, the alteration of cellular function induced by FGFR pathway activation might instead be affected by the status of a network consisting of various signaling cascades such as other receptor tyrosine kinases, WNT, Notch, and TGFβ in each cancer cell [41].