at the transcriptional level, the expression of p-gp has been intensively studied, and numerous transcription factors and pathways are known to play roles. a variety of transcription factors, such as p53, yb-1, and nf-κb are involved in the direct regulation of p-gp by binding to the promoter regions of the p-gp gene. many cell signaling pathways are also involved in transcriptional regulation of p-gp. for example, the pi3k/akt pathway and the wnt/β-catenin pathway were reported to positively regulate the expression of p-gp. mitogen-activated protein kinase (mapk) signaling includes three pathways: the classical mapk/erk pathway, the p38 mapk pathway, and the c-jun n-terminal kinase (jnk) pathway, all of which were reported to have implications in the regulation of the expression of p-gp. studies suggested that the mapk/erk pathway is involved in the positive regulation of p-gp; the p38 mapk pathway negatively regulates the expression of the p-gp gene; and the jnk pathway was reported to be involved in both positive regulation and negative regulation of p-gp.