May be involved in testis development (By similarity). May play a role in hematopoietic differentiation or inflammation (PubMed:12535658). Has immunomodulatory and antimicrobial functions against Francisella tularensis, a Gram-negative bacteria (PubMed:23922243). May be targeted through the Golgi via the secretory pathway. Expressed in heart, placenta, lung, liver, skeletal muscle and pancreas (PubMed:12535658). Not expressed in brain (PubMed:12535658). Expressed in epididymis, kidney, testis, spinal cord, and thymus with a strong expression in epididymis and kidney and a weak expression in the spinal cord and thymus (PubMed:20565543). Up-regulated by bacterial lipopolysaccharides (LPS), in some cancer cells such as promyelocytic leukemia cells (HL-60) or myelomonocytic leukemia cells (U-937). Belongs to the cystatin family.