SPAG11B is a 103 amino acid precursor protein that exists as four alternatively spliced isoforms, designated EP2A, EP2B, EP2C and EP2D, all of which are androgen-dependent, epididymis-specific secretory proteins that may play a role in sperm maturation and overall function. The gene encoding the SPAG11B precursor maps to a region on chromosome 8 that is near the ∫-defensin gene cluster and it is suggested that SPAG11B may exhibit functional characteristics (such as antimicrobial activity) that are similar to ∫-defensins. Human chromosome 8, on which the SPAG11B gene is localized, consists of nearly 146 million base pairs and houses more than 800 genes, some of which are associated with a variety of diseases and malignancies.