Meanwhile, prolonged activation of PI3K/AKT and ERK signaling disrupts the regulation of cell growth and division, leading to the characteristic features of Noonan syndrome (OMIM# 163950) that is caused by germline variation in KRAS genes (PTPN11, SOS1, RAF1, LZTR1, etc.)[26]. This evidence concerns the gene SOS1 and Noonan syndrome.