To investigate whether inactivation of the Testisin gene may confer a selective advantage to testicular tumorigenicity, the effect of expression of the Testisin gene in Tera-2 cells, which lack Testisin gene expression and form tumours when implanted in an orthotopic model of testicular tumorigenesis (Douglas et al, 2001), was investigated. Here, PRSS21 is linked to neoplasm.