Cell-based selectivity testing of the SAHA analogues. U937 cells were treated with (a) DMSO (1%), SAHA (2 μM), tubastatin (2 μM), C2-benzyl SAHA (1g, 30 μM), C2-n-pentyl SAHA (1h, 30 μM), C2-n-hexyl SAHA (1i, 30 μM), or (c) increasing concentrations of C2-n-hexyl SAHA analogue (1i, 10–60 μM) before lysis, SDS-PAGE separation, and Western blot analysis of acetyl-histone H3 (AcH3) and acetyl-α-tubulin (AcTub). GAPDH was a load control. Repetitive trials are shown in Figures S49 and S50. (b) Fold increase in AcH3 or AcTub after quantification of band intensities from part a, with mean fold increase from four independent trials and standard error (Table S10).