Axl Proteins

Axl is the best-characterized member of the TAM family of receptor tyrosine kinases and the highest-affinity receptor for the vitamin K-dependent ligand Gas6. Gas6-Axl engagement activates PI3K-AKT, RAS-MAPK, and STAT signaling that promotes cell survival, migration, and immune modulation. Expression is low in most resting tissues but rises sharply during epithelial-to-mesenchymal transition, tissue injury, and malignant transformation. Axl upregulation is a recognized mechanism of resistance to EGFR, HER2, and BRAF inhibitors, and shed soluble Axl serves as a disease biomarker. Selective inhibitors such as bemcentinib and Axl-directed antibodies are in clinical development across solid tumors and leukemia.