Cell proliferative potential as a function of B7-H1 expression in MDS cell lines. (A-B) Cell-cycle analysis of B7-H1⁺ and B7-H1⁻ cell fractions in F-36P (A) and SKM-1 (B) cells. SKM-1 cells were cultured with IFNγ for 2 days before analyses. (C) BrdU incorporation in B7-H1⁺ and B7-H1⁻ cell fractions in F-36P and SKM-1 cells. (D) The number of colonies formed by purified B7-H1⁺ and B7-H1⁻ F-36P cells in the methylcellulose culture. Data in panels A through C are mean (and SD) of 3 experiments. *P < .036 for B7-H1⁺ versus B7-H1⁻ cell fractions.