A) Cell based selectivity testing of the C4-benzyl SAHA analog 1f. Western blot analysis of acetyl-histone H3 (AcH3) and acetyl-α-tubulin (AcTub) is shown after treatment with SAHA or the C4-benzyl SAHA analog 1f. U937 cells were treated with DMSO (1%), SAHA (5 μM), or increasing concentrations of C4-benzyl SAHA (1f) analog (20-60 μM), before lysis, SDS-PAGE separation, transfer to a PVDF membrane, and western analysis with AcH3 or AcTub antibodies. GAPDH levels in the samples were also probed as a gel load control. A DMSO control sample was included for comparison to inhibitor treated samples. Repetitive trials are shown in Figure S149. B) Cytotoxicity of tubastatin (Tub) and PCI-34051 (PCI) alone or in combination using an MTT assay with the U937 cell line. Concentrations close to the EC50 values of each inhibitor were used (80 μM for tubastatin and 200 μM for PCI-34051). Mean percentage cell viability from three independent trials with standard errors was plotted (Table S12).