Fig 2: PPA2 expression is significantly lower in KIRC tissues than in normal tissues.(A) Representative images of immunohistochemically-stained tumor tissues and normal tissues. Case 1 was derived from a tissue microarray which contained 150 tumor tissues and 30 normal tissues, whereas Case 2 represents another cohort from Meizhou People’s Hospital which contained 10 tumor tissues and paired normal tissues. (B) Differential PPA2 expression in TCGA KIRC cohort. (C) PPA2 expression was significantly different among patients with different cancer stage. B and C represent the results of analyses carried out on the GEPIA2 platform. KIRC, kidney renal clear cell carcinoma; KIRP, Kidney renal papillary cell carcinoma; KICH, Kidney chromophobe; IHC, immunohistochemistry.

Fig 3: Association between PPA2 expression and the OS of KIRC patients.(A) Low PPA2 expression at the protein level is significantly correlated with poor OS. (B) Validation of the correlation between PPA2 expression and OS on the GEPIA2 platform. KIRC, kidney renal clear cell carcinoma; OS, overall survival.

Fig 4: Independent prognostic value of PPA2 in KIRC.(A) Forest plot showing the results of univariate Cox regression analysis. (B) Forest plot showing the results of multivariate Cox regression analysis. (C) Kaplan–Meier survival analysis for PPA2 expression stratified by histologic grade. (D) Kaplan–Meier survival analysis for PPA2 expression stratified by stage. KIRC, kidney renal clear cell carcinoma.

Fig 5: Results of gene set enrichment analysis (GSEA).(A) Bubble chart showing the top activated and suppressed signaling pathways in KIRC tissues with decreased PPA2 expression. (B) Enrichment plot showing three selected representative pathways. KIRC, kidney renal clear cell carcinoma.