Thus, we examined the effect of type I IFN on MARCH2 expression levels in H9 cells, a human T lymphocytic cell line, and phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 cells, a human monocytic cell line, both cell lines susceptible to HIV-1 infection, as well as 293T cells after treatment with human IFN-β (500 U/ml) (PBL Assay Science). Here, IFNB1 is linked to HIV-1 infection.