MAPK3 and prostate cancer: β-Ionone stimulation robustly activated ERK1/2 in HEK293 cells expressing FLAG-OR51E2 (Figures 1D,E), suggesting that, similar to endogenous OR51E2 in prostate cancer cells, exogenous FLAG-OR51E2 is fully capable of activating ERK1/2 in HEK293 cells.