In terms of renal cell carcinoma (RCC), clinical experimental studies have proven that some KLKs, such as KLK1, KLK3, KLK6, KLK7, and KLK15, are differentially expressed in different subtypes of RCC, and KLK6 has predictive value in RCC [7, 8]. This evidence concerns the gene KLK1 and renal cell carcinoma.