PGP and cancer: Curcumin is a “privileged structure” that is able to affect different pathways deregulated in cancers; it suppress the activation and expression of numerous factors responsible for proliferation, drug resistance, and apoptosis inhibition—such as AP-1, MAPK, Akt, COX-2, P-gp and, in particular, NF-κB—through IκB phosphorylation inhibition [85,86].