PAK4 and bladder transitional cell carcinoma: As shown in Fig. 1A, Pak4 was highly expressed in various tumors, including bladder urothelial carcinoma (BLCA), breast invasive carcinoma (BRCA), cholangiocarcinoma (CHOL), Esophageal carcinoma (ESCA), head and neck cancer (HNSC) and so on.