PGP and cancer: Over time, cancer cells can develop resistance to a wide range of compounds by the upregulation of Pgp expression (Abdallah et al., 2015 ▸; Gottesman & Ling, 2006 ▸; Roninson et al., 1984 ▸, 1986 ▸; Shen et al., 1986 ▸; Ueda et al., 1986 ▸).