MMP9 and neoplasm: Beside the observed PHLPP1 mutations, additional genes related to the RET signaling pathway were detected and classified into Tier 3, both in primary and relapse tumor samples: ERBB3, MET, PDGFB, RET, IRS2, DUSP10, AKT1, RIT1, MAPK7, NFKB1, MAP2K7, MAP2K4, MEF2C, and MMP9.