First, MEC cells displayed histological features of cytokeratin patterns similar to normal salivary gland stem cells which reside in the ductal areas.17–21 Second, the CRTC1-MAML2 fusion was detected in all three major cellular components within MEC tumors, suggesting that salivary gland stem/progenitor cells after the initiation of the CRTC1-MAML2 oncogenic fusion event differentiate to various cellular components in human MEC. This evidence concerns the gene CRTC1 and mucoepidermoid carcinoma.