Other cell cycle-associated genes identified as playing significant role in HIV-1 infection include p21/CDKN1A, which acts as an intrinsic inhibitor of HIV-1 reverse transcription in CD4+ T cells of elite controllers (22); and cyclin A2 (23) and cyclin L2 (24), which are exploited by HIV-1 to evade the restriction function of SAMHD1 in different cell types, thereby enabling the virus to replicate efficiently. Here, CD4 is linked to HIV-1 infection.