PIK3R1 and renal cell carcinoma: In order to reveal the functional influence of PIK3R1 depletion, a CRISPR/Cas9 strategy which was designed according to the nonsense mutation reported previously14, was applied to induce a haploid deletion mutation in order to achieve haploid knockout of PIK3R1. Firstly, we analyzed the expression levels of PIK3R1 in normal renal cell line (HK2) and RCC cell lines (786-O, A-498, A-704, and ACHN) by using RT-PCR.