B7-H6 expression in tumor cell lines is downregulated by treatment with HDACi. HeLa, SK-Mel-37, HepG2, Ramos, and K562 cells were treated for 16 hours with the pan-HDACi SAHA or solvent control (DMSO). (A) Treated cells were stained with anti–B7-H6 mAb 1.18, mIgG1 isotype control, NKp30-FP, NKG2D-FP, and a control-FP for flow cytometry. Dead cells were excluded by gating on 7-AAD⁻ cells. Representative histograms of at least 2 independent experiments are shown. The mean geometrical mean and % reduction in B7-H6 surface expression after SAHA treatment ± standard deviation (SD) from at least four 4 experiments is shown. **P ≤ .01; ***P ≤ .001. (B) B7-H6 mRNA expression in treated cell lines was determined by qRT-PCR. Mean (expression of B7-H6 relative to GAPDH) and % reduction in B7-H6 mRNA expression after SAHA treatment ± SD of duplicates is shown for 1 representative experiment out of 2. The values from DMSO treatment were set as 100%.