IGF1R and neoplasm: Moreover, overexpressed GAS5 combined with gefitinib-treatment therapy reduced tumor growth in vitro and in vivo and confirmed that IGF-1R (Insulin-Like Growth Factor 1 Receptor) is a downstream key mediator, with a negative correlation with GAS5 expression, and involved with the physiological phosphorylated levels of the p-EGFR, p-Akt, and p-ERK proteins (Fig. 3).