MYO1B encodes myosin IB, a membrane-associated actin motor protein that regulates multiple cellular processes critical for tissue homeostasis and pathological states. Primary function: MYO1B functions as an actin-based motor protein participating in vesicular trafficking, membrane dynamics, and cell polarity establishment 1. In intestinal epithelial cells, MYO1B regulates lumen formation, Golgi organization, and apical targeting of membrane mucins including MUC17, working alongside MYO5B and sorting nexin SNX27 to maintain brush border organization 2. Mechanism: MYO1B interacts with UNC45A and regulates autophagosome-lysosome fusion through interactions with LRRK2, controlling intracellular calcium levels and HIF-1α stability 34. Disease relevance: MYO1B dysregulation is implicated in multiple cancers—colorectal, esophageal squamous cell, cervical, and oral carcinomas—where elevated expression correlates with poor prognosis and promotes tumor progression via SNAI2/cyclin D1 and VEGF-mediated angiogenesis pathways 5367. Clinical significance: MYO1B deficiency causes enterocyte polarity defects resembling villous atrophy 1, while MYO1B upregulation promotes endothelial senescence and vascular aging 4. MYO1B represents a potential therapeutic target in cancer and age-related vascular disease.