There are 3 MAML (mastermind-like) proteins in mammals (MAML1-3). MAML2 is a critical coactivator for NOTCH signaling. MAML2 associates with NOTCH and CSL in a ternary complex and functions to activate transcription of HES and hairy-related basic helix-loop-helix transcription factors. MAML2 has been identified in a chromosomal rearrangement and fusion with MECT1 in mucoepidermoid carcinomas, secondary acute myeloid leukemia, hidradenomas, and myelodysplastic syndrome. MECT1 is a CREB regulator, and when fused with the transactivational domain of MAML2, imparts constitutive activation of CREB-dependent transcription that may promote oncogenesis.