To prioritize protein biomarkers for IUP diagnosis, the top 10 candidates selected by machine learning analysis between IUP and PUC were further shortlisted, based on the t-test FDR and the machine learning rank order (Figure 4A), resulting in the five most robust proteins; SERPINH1, ALDH1L1, PKP2, OGDH, and PYGB (Figure 4B). This evidence concerns the gene ALDH1L1 and inverted urothelial papilloma.