SIGIRR and kidney cancer: A trend toward lower levels of SIGIRR mRNA expression was observed in patients with shorter overall survival in a large cohort of cases including all the different kidney cancer types from TCGA database (Supplementary Figure S4); however, when the analysis was performed by dividing the different tumor subtypes, no difference was observed among cases expressing different levels of SIGIRR, suggesting that SIGIRR downregulation specifically marks a clear cell RCC histotype (the most aggressive subtype) rather than overall survival.