Expression of Fs antigen in transfected MEG-01 measured by flow cytometry. The bar graph shows the mean percentage of Fs-positive cells after 3 independent transfection experiments, each performed in triplicate with the open reading frame of B3GALNT1 and either GBGT1 887A (Fs mut) or 887G (Fs WT). As a negative (background) control included in all 3 experiments, cells were transfected with the empty vector without insert (mock) and run in duplicate. The mean percentage of Fs-positive cells among the viable transfected (GFP-positive) cells is shown. Non-viable cells were disqualified by exclusion gating of cells positive for 7AAD. Error bars depict the standard error of the mean (SEM). The difference in Fs antigen expression after transfection was calculated to be statistically significant for the Fs mutant compared with the Fs wild-type cells and mock-treated cells according to the independent Kruskal-Wallis test. The significance level for the difference between wild-type and mutant is shown by the asterisks above the bars. Data were considered statistically significant with respect to the following criteria: *P < .05, **P < .01, and ***P < .001.