PPY and urinary bladder carcinoma: Our IRG-based signature highlighted eleven IRGs, ADIPOQ, PPY, NAMPT, TAP1, AHNAK, OLR1, PDGFRA, IL34, MMP9, RAC3, and SH3BP2. Several studies showed that upregulation of MMP9 could promote the proliferation and invasion of bladder cancer [25, 26].