MBP and nonpapillary renal cell carcinoma: 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.