Inhibition of c-KIT and erythropoiesis. (A) TF-1 cells, which express WT c-Kit, were treated with crenolanib or quizartinib for 1 hour. In the last 5 minutes of drug treatment, 20 ng of stem cell factor was added. The cells were lysed, immunoprecipitated for c-Kit, and analyzed by immunoblot for phospho- and total c-Kit. (B) Normal human donor bone marrow (n = 3) was collected and diluted to a concentration of 100 000 cells per mL in MethoCult. Various concentrations of crenolanib or quizartinib were added, and cells were plated in quadruplicate in 35-mm dishes. Each dish was viewed under a light microscope, and total numbers of granulocyte-macrophage colony-forming unit and erythrocyte burst-forming unit colonies were recorded.