Bromodomain inhibition is reversible and “memory” of the active ES is retained.

(A) Flow cytometry measuring the amount of anti-VSG antibody bound to the cell surface as well as surface levels of EP1 following treatment with I-BET151 for the indicated number of days. (B) Flow cytometry measuring surface levels of VSG and EP1 following a 5-d treatment with I-BET151, washout, and recovery for 3 d (top two panels) or 4 d (bottom two panels). Numerical data for Fig 4 is in S4 Data.