CDKN2A and infection: More importantly, the treatment of stably infected HIV-1 cell lines, J1.1 and U1, with exogenous p16INK4A resulted in a decrease in viral replication with a minimal decrease in cellular viability, suggesting that the presence of p16INK4A in the context of an in vitro HIV-1 infection may mimic an in vivo infection in a LTNP patient.