We studied 80 primary and 12 metastatic ccRCC tumors and identified 7 peptide substrates with significantly increased tyrosine phosphorylation by metastatic samples relative to primary tumor samples including FGFR1, FAK1, ACHD, K2C8, EGFR, EPHB4 and MBP. Here, PTK2 is linked to nonpapillary renal cell carcinoma.