ERG and neoplasm: We expanded the work to 2 other models, 287R, and 435.1A (Supplementary Fig. 3): 287R-Cx was derived from a castration-sensitive tumor obtained via radical prostatectomy and is positive for AR, PSA, PSMA, and ERG but negative for neuroendocrine markers, whereas the 435.1A-Cx model was derived from a CRPC brain metastasis and is representative of AR-negative NEPC [51].