Fluphenazine is a traditional antipsychotic compound that tightly binds the dopamine D2 receptor (Ki = 0.55 nM) and also reversibly inhibits calmodulin at micromolar concentrations. Fluphenazine-N-2-chloroethane is a derivative of fluphenazine that contains an alkylating chlorethylamine chain, which produces irreversible protein binding. It is a relatively selective, irreversible antagonist of D2 receptors both in vitro (IC50 = 100 nM) and in vivo, inactivating approximately 90% of D2 receptors in mice within 4 hours of treatment. Through this action, fluphenazine-B-2-chloroethane can be used to induce catalepsy in mice. It irreversibly inhibits calmodulin at higher doses (IC50 = 10 μM), which can sensitize cancer cells to TRAIL-induced apoptosis.