AXL and small cell lung carcinoma: EGFR-independent ARMs involve bypass signaling activation (MET, HER2 and FGFR amplifications, as well as ALK, ROS1 and RET rearrangements), epithelial-to-mesenchymal transition (EMT) through AXL receptor tyrosine kinase (AXL) activation, SCLC transformation and downstream pathway activation, such as PI3K mutations, and RAS–MAPK pathway activation, including BRAF mutations and rearrangements [8,28].