PRSS50 and breast neoplasm: In addition to its expression in normal testes, TSP50 is abnormally reactivated in many malignant breast tumor samples and colorectal carcinoma biopsies tested.17, 18, 19 Our previous studies revealed that knockdown of TSP50 inhibited cell proliferation and induced apoptosis in p19 and MDA-MB-231cell,20, 21 and overexpression of TSP50 efficiently promoted cell proliferation in vitro and stimulated tumor formation in nude mice.