The lysosome associated protein transmembrane (LAPTM) family is comprised of three members: LAPTM5, LAPTM4a and LAPTM4b; they are lysosome-associated transmembrane proteins, found in mammals, insects and nematodes.This entry represents LAPTM4 beta (LAPTM4B). Overexpression of LAPTM4B has been show to be involved in carcinogenesis [], and polymorphisms in the gene have been asssociated with an increased susceptibility to gastric cancer []. In normal cells, LAPTM4B may play a role in the regulation of cell proliferation and survival [].