The role of the tumor environment in CRPC response to MKI was also suggested by 2 long-term (300-day) studies, in which 22Rv1 xenografts in castrated nude mice were treated with SNX631 either for the first 38 days or for the entire 300-day period (such an exceptional length of continuous drug treatment reflects the lack of toxicity of selective CDK8/19i). The gene discussed is CDK8; the disease is neoplasm.