Expression of STAT3 and STAT5 has been demonstrated in PC cell lines [32, 35, 37] and PC tissues [30, 31, 33, 34, 36, 38]; however, the expression of STAT3 and STAT5A in metastatic CRPC has been rarely studied [31, 33, 38]. This evidence concerns the gene STAT5A and pachyonychia congenita.