MTOR and gastric cancer: Multiple evidence connects DDR2 and EMT to tumor aggressiveness across cancer types, as in metastatic melanoma, where it sustains the EMT-like process of phenotype switching and MAPK pathway activation and proliferation in melanoma BRAF-resistant cells [51], or in gastric cancer where DDR2 promotes stemness maintenance and EMT of gastric cancer stem cells by mTOR-SOX2 axis [52].