Fig. 2.

CT mutations increase surface expression of Envs in plasmid-transfected HEK 293T cells. The indicated CT mutations were made in four HIV-1 Envs: (A) R3A, (B) JRFL, (C) 89.6 WT, and (D) 89.6 N7 (N₁₉₇Q). HEK 293T cells were co-transfected with plasmids encoding GFP and Env and at 18 h were stained for Env using mAb 2G12 under non-permeabilizing (surface stain) and permeabilizing (total stain) conditions. Data represent the average fold change in Env-specific mean fluorescence intensity (MFI) of GFP⁺ cells relative to parental Env in each experiment, with N = 3 (A, B, D) or N = 4 (C) replicates. Asterisks indicate Env variants that showed a significant fold difference (p < 0.05) in surface expression compared to the parent Env (normalized to 1) by one-sample t-test on log-transformed data with Bonferroni correction.