To further validate the aforementioned bioinformatics analysis, the mRNA expression levels of these hub genes (MCL1, IGF1R, CCND1, and PTEN) were obtained by RT-qPCR experiment in cisplatin resistant RCC cell lines (786-O and A-498) and a normal control cell line (HK-2). This evidence concerns the gene IGF1R and renal cell carcinoma.