However, none of the four major HCV-entry cofactors, SR-B1, CD81, CLDN1 and OCLN, was differentially expressed between the tumor and the nontumorous tissue, as also confirmed by real-time PCR analysis (Fig 1D), thus ruling out a role of downregulation of these major entry cofactors in the restriction of HCV replication within the tumor. Here, CD81 is linked to neoplasm.