The armadillo (ARM) repeat family of proteins are related to the Drosophila melanogaster armadillo protein, a protein essential for wingless signal transduction. ARM proteins are involved in a variety of processes such as cell migration, cell proliferation, tissue maintenance and tumorigenesis, and they also function in signal transduction and the maintenance of overall cell structure. ARMCX2 (armadillo repeat containing, X-linked 2), also known as ALEX2, is a 632 amino acid single-pass membrane protein that contains three ARM repeats and is highly expressed in testis, brain, ovary, heart, colon, spleen and prostate, where it is thought to play a role in tumor suppression. The gene encoding ARMCX2 maps to human chromosome X, which contains nearly 153 million base pairs and houses over 1,000 genes.