PIK3CA and cancer: One of the most important receptor tyrosine kinases to have a role in cancer cell proliferation is EGFR, the epidermal growth factor receptor, a transmembrane glycoprotein member of the ERBB receptor tyrosine kinase superfamily leading to a phosphorylation cascade mediated via tyrosine kinases which works downstream through the PI3K–PTEN–AKT, MAPK, ERK, and JAK/STAT pathways and promotes proliferation, invasion, angiogenesis, and metastatic spread.