FIG. 5.
Enhancer-dependent oscillations are eliminated by a histone deacetylase inhibitor. (a) TSA dose response. Cells (5 × 104/ml) were incubated with increasing amounts of TSA, or with 2% DMSO, for 6 days. The cells were then counted (line graph), and the percentage of cells induced to differentiate was evaluated by benzidine staining (bar graph). Concentrations below 20 nM did not induce differentiation and were not cytotoxic. (b) TSA eliminates oscillations of β-globZ. MEL cells with cassettes 0, 2, 3, and 234 at RL1 were incubated with 5 nM TSA, and β-globZ expression was monitored by FACS-Gal. Regardless of the cassettes at RL1, the proportion of expressing cells gradually increased. (c) Minimum response times to TSA. Cells with cassette 0, 2, 3, or 234Neo were incubated with 5 nM TSA for 6 h and tested by FACS-Gal. An increase in the percentage of positive cells could be clearly detected after 6 h.