MAML1, also named as KIAA0200 and Mam-1 , belongs to the mastermind family. It acts as a transcriptional coactivator for NOTCH proteins. MAML1 has been shown to amplify NOTCH-induced transcription of HES1. It enhances phosphorylation and proteolytic turnover of the NOTCH intracellular domain in the nucleus through interaction with CDK8. MAML1 binds to CREBBP/CBP which promotes nucleosome acetylation at NOTCH enhancers and activates transcription. Induces phosphorylation and localization of CREBBP to nuclear foci. It plays a role in hematopoietic development by regulating NOTCH-mediated lymphoid cell fate decisions. The calculated molecular weight of MAML1 is 108 kDa, but modified MAML1 is about 120-130 kDa.