TWIST1 and neoplasm: In tumor cells, activation of Axl has been associated with downstream signaling of proliferation and survival pathways such as Erk and Akt35, 36, 37, 38, emergence of drug resistance via the direct phosphorylation of other tyrosine kinases such as MET and EGFR23, 39, and epithelial to mesenchymal transition (EMT) via the up-regulation of TWIST and SLUG14, 40, 41.