MYO5B is a member of the class V of unconventional, dimeric nonfilamentous myosins, which may be involved in vesicular trafficking. Members of the Rab family of small GTPases, consisting of Rab11a, Rab11b, and Rab25, have recently emerged as potential mediators of vesicle transport by MYO5B (PMID: 21282656). MYO5B is required for polarization of hepatocytes and mutations of MYO5B could disrupt epithelial cell polarity. Loss-of-Function of MYO5B caused by mutation is the main cause of microvillus inclusion disease (MVID). Recently it was reported that the expression of MYO5B was downregulated in gastric cancer and inactivation of MYO5B may contribute to tumorigenesis (PMID: 22134786).