Of the 150 genes that were upregulated in untreated PC compared to CRPC, and downregulated with castration in PC xenografts, 16 core genes consistently re-emerged with castration resistance: PECI; TNFSF10; ABHD12; XRCC3; MAD1L1; SEC61A1; GFM1; TSPAN13; STIL; TRMT12; EIF2B5; TM4SF1; NDUFB11; SLC26A2; AGR2; NT5DC3. Here, AGR2 is linked to pachyonychia congenita.