PDGFRA (platelet-derived growth factor receptor alpha) is a receptor tyrosine kinase, which activates PI3K/Akt, RAS/MAPK, and JAK/STAT pathways to promote cell proliferation and survival. Simple variants in PDGFRA are seen in about 4% of all tumors, including 5% of gastrointestinal stromal tumors (GIST) and 25% of tumors in the small intestine, where it helps with diagnosis. In GIST, specific mutations predict resistance versus response to PDGFR inhibitors.