AR and Familial prostate cancer: As mentioned above, the high alteration frequency of MLL1‐fusion partners in NEPC and their interactions with androgen‐receptor signaling pathway components (Figs 1 and S4), which are important in prostate cancer progression (Mazaris and Tsiotras, 2013; Ramsay and Leung, 2009), prompted us to explore the tumor sequencing data from TCGA to identify gene fusions of MLL1 in prostate cancer.