CHMP1a (Charged Multivesicular Body Protein 1a) is a protein encoded by the CHMP1A gene in humans and belongs to the ESCRT-III (Endosomal Sorting Complex Required for Transport) family. It plays a crucial role in the formation and sorting of multivesicular bodies (MVBs), which are involved in the degradation of proteins in lysosomes. CHMP1a is also known as Chromatin Modifying Protein 1A and has been identified as a novel tumor suppressor gene, particularly in pancreatic and embryonic kidney tumor cells. It can inhibit cell proliferation and tumor growth by regulating the expression of proteins like p53. Additionally, CHMP1a interacts with other proteins such as SKD1 and LIP5, which are involved in the endosomal sorting process.