Using 23 prostate cancer and 31 benign tissue samples as a validation set, they confirmed an expression profile that discriminates between prostate cancer (GS6–7) and normal tissue, further identifying mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase 2 (MEKK2) as a marker to discriminate cancer from uninvolved tissue. Here, MAPK1 is linked to prostate cancer.