In the 12 primary lung tumors analyzed, 8 were positive for increased phosphorylation of p90RSK (66.7%); in the 12 melanomas analyzed, 10 were positive for increased phosphorylation of p90RSK in tumor tissues compared to normal counterparts (83.3%); all five prostate tumors were negative for increased phosphorylation of p90RSK (100%). Here, RPS6KA1 is linked to prostate neoplasm.