In lung cancer, GLI Family Zinc Finger 2 (GLI2) acts as the downstream gene of FGF19/FGFR4, and GLI2 can directly transcriptionally upregulate FGF19 expression, forming the FGF19-GLI2-FGF19 feedback loop to promote metastasis 52. Here, FGFR4 is linked to lung carcinoma.