This effect was specific to mutations that affected binding by RANBP2-Cyp, since both infectivity and MX2 sensitivity of HIV-1WT were similar in control and RANBP2K3129H cells, and suggests that the effects of deletion of the Cyp domain of RANBP2 on HIV-1 infection and MX2 sensitivity are the direct result of abrogating CA-RANBP2-Cyp interactions (although we cannot definitively exclude the possibility that RANBP2D3126N affects interactions with a cellular substrate relevant for HIV-1 CA-MX2 interactions). The gene discussed is RANBP2; the disease is HIV-1 infection.