(A) PC9 cells were either untreated or treated singly with the indicated pharmacological agents for 6 days (top rows) or with erlotinib (ERL) alone or the combination of the indicated pharmacological agent with erlotinib for 33 days (bottom rows). Fresh media with drugs was provided every three days. Following treatment, plates were fixed and Giemsa stained. All experiments were performed in triplicate and representative plates are shown.
(B) Individual colonies were counted and the quantified results were graphed. In some cases the colonies were too numerous to count (indicated as >500 colonies). Results reflect the mean and standard deviation from triplicate samples.
(C) PC9 cells were either treated with 2μM of erlotinib (ERL) for 25 days or pre-treated for 9 days with 20nM of TSA and then treated with 2μM of erlotinib for 25 days. In parallel, PC9 cells were also treated continuously with 20nM TSA for 25 days (~ 4 passages). After 25 days, plates were fixed and Giemsa stained. The experiment was performed in triplicate and representative plates are shown.