As these findings suggest, the difference in TRN-SR2 dependency displayed by the N74D CA mutant in the multiple round compared with the single round infections was dependent on the envelope proteins; we investigated prolonged multiple round replication of the HIV-1 N74D CA mutant carrying a wild type envelope using HeLaP4 cells stably depleted of TRN-SR2 knockdown. This evidence concerns the gene TNPO1 and infection.