PGP and cancer: Because the mechanisms for ribociclib to downregulate ABCB1 and inhibit P-gp mediated MDR in cancers could be associated with many aspects, we are currently performing experiments, including real-time PCR of ABCB1 in ribociclib treated cells, or transcriptome sequencing and quantification, in addition to Western blot and immunofluorescence which we have done, to explore the ABCB1 expression at the transcription level.