JAK2 and lung cancer: We then tested co-occurrence or mutual exclusivity of the JAK2 p.V617F mutation with other well-characterized lung cancer genes including RAS family genes (KRAS, NRAS, HRAS), EGFR, BRAF, and HER2. As expected, mutations in the RAS genes, EGFR, BRAF, and HER2, are largely mutually exclusive.