The presence of a number of different FGFR ligands suggests that all four FGFRs can potentially be activated by autocrine mechanisms in NSCLC, with FGFR1 non-amplified cells secreting ligands that can activate FGFR2, FGFR3 and FGFR4. This evidence concerns the gene FGFR4 and non-small cell lung carcinoma.