PIK3CA and cancer: Moreover, being key components of cell signaling systems, these RTKs control major downstream signaling pathways, i.e. Ras/Raf/MAPK (in KEGG and WikiPathway), PI3K-Akt (in KEGG and Reactome), FoxO (in KEGG), and Jak-STAT (in KEGG) that are crucial for cancer cell growth and survival [3].