MLN4924 inhibits HIV-1 infection of PMA-differentiated THP1 cells. HEK293T cells (A) or PMA differentiated THP-1 cells (B) were pre-treated with 1 μM MLN4924 for three hours, and infected at an equivalent MOI with env(−), VSV-G-pseudotyped-HIV-1 or -HIV-1 lacking Vpr. All viral constructs expressed GFP in place of Nef. Forty-eight hours post infection, cells were fixed, and infectivity was determined by enumerating GFP-expressing cells using flow cytometry. Panel C summarizes data from multiple replicates of experiments performed as indicated for panel B. Error bars show standard deviation. The two-tailed Student’s t-test was used to determine whether differences between pairs of conditions are statistically significant. ns indicates comparisons where the differences were not significant at a level of 0.05.