Furthermore, the testis-specific TSP50 promoter is occupied by both CTCF and BORIS proteins in all three human cancer cell lines, thereby representing a bona fide CTCF&BORIS bound region with two conserved individual CTCF sites located 58 and 33 base pairs (bp) apart in the human and mouse promoters, respectively (Fig. 2a). Here, PRSS50 is linked to cancer.