There are 3 MAML (mastermind-like) proteins in mammals (MAML1-3). MAML1 is a critical coactivator for NOTCH signaling. MAML1 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. MAML1 has been observed to interact with p300 to acetylate histones H3 and H4. MAML1 also interacts with p53 and functions independent of NOTCH signaling, as a coactivator of p53 target genes.