PGP and familial pancreatic carcinoma: Furthermore, it is well documented that ABCG2 as a critical efflux pump protein plays a vital role in maintaining viability of latent stem-like cancer cells [23–29], and the increase of ABCG2 [13–17], Pgp [18–21] expression is important for pancreatic cancer resistance to commonly used pancreatic cancer drugs in the clinic.