FLT3 and acute lymphoblastic leukemia: For instance, frequency of common childhood ALL gene deletions, including CDKN2A, IKZF1, and PAX5, is relatively low [12], whereas activating mutations in receptor tyrosine kinase (RTK)/Ras/MAPK signaling genes KRAS, NRAS, FLT3, and PTPN11, are relatively common [13-15].