The mechanism of SFI showing synergistic efficacy on cells with Gefitinib is inhibiting MAPK/SREBP1 pathway. (A, B and C) Western blotting was performed to determined p-EGFR, EGFR, p-MEK, MEK, p-ERK, ERK protein expression after being treated with SFI (1:10) and Gefitinib 4 μM alone or in combination in PC-9/GR, H1975 and H1650 cells. ###p<0.001 compared to control group. $$$p<0.001 compared to control (EGF) group. ***p<0.001 compared to combination group. (D, E and F) Western blotting was conducted to detect flSREBP1 and mSREBP1 protein expression after being treated with SFI (1:10) and Gefitinib 4 μM alone or in combination in PC-9/GR, H1975 and H1650 cells. *p<0.05, **p<0.01 or ***p<0.001 compared to combination group.