PIK3R1 and cancer: The binding of a ligand to EGFR leads to proliferation, differentiation and inhibition of apoptosis through the activation of different pathways, such as MAPK, phosphatidylinositide 3-kinases (PIK3), signal transducer and activator of transcription (STAT), cyclin-dependent kinase 6 (CDK6), PIK3R1 and PTEN. Additionally, hsa-miR-21-5p has been found, deregulated in pediatric cancer stem cells and in clear renal cell carcinoma (RCC) (38,39).