Moreover, it was reported that MEK inhibitor could induce transcriptional upregulation of endogenous BCRP through the inhibition of the MEK-ERK-RSK pathway, but promote post-transcriptional protein degradation of endogenous BCRP through the inhibition of the MEK-ERK-non-RSK pathway in breast cancer cells [39]. The gene discussed is ABCG2; the disease is breast carcinoma.