Reversal of HDAC protein loss upon SFN removal. (A) HCT116 cells were treated as described in Figure 1 legend, except that in some cases the SFN was removed after 6 or 24 h and replaced with fresh media containing no SFN. HDAC activity was determined for whole cell lysates obtained 24, 48 or 72 h after SFN was first added to the cells. Data (mean ± SE, n = 3) are from a single experiment, and are representative of the findings from three separate experiments. **P < 0.01 versus the corresponding DMSO control. (B) Whole cell lysates corresponding to the HDAC assay in (A) were immunoblotted for selected HDACs.