The human mastocytosis cell lines HMC1.2, harboring a KIT V560G and a D816V mutation, and the murine cell line p815 (harboring a Kit D814Y mutation analogous to the human D816Y mutation) were treated with crenolanib in a dose-dependent manner for 48 hours and the cellular anti-proliferative capacity was measured using an XTT-based assay. The gene discussed is KIT; the disease is mastocytosis.