Remarkably, initial observations also show that many more polar phenolic SM (phenolic acids, flavonoids, xanthones, chalcones, catechins, anthocyanins, tannins, stilbenes, anthraquinones, and naphthoquinones) (El-Readi et al., 2019) can directly disrupt the 3D structure of P-gp, thus inhibiting its activity in MDR cancer cells (Wink, 2008). Here, PGP is linked to cancer.