Thisscreen identified several proteins, including Rab5A, Snx3 and Snx10,knockdown of which in a CD4+ T-cell line significantly reduced HIV-1fusion and infection.21 Intriguingly, HIV-1fusion in endosomes has been shown in target cells after virologicalsynapse mediated transfer from donor cells.22 The common caveats of arguments for and against endocytic HIV-1entry are the reliance on bulk virus uptake (and fusion) and assessmentof the virus’ apparent colocalization with intracellular markerswithout following the functionally relevant infectious events. Here, CD4 is linked to infection.