Pyrimidines, quinazolinones, and nucleosides could inhibit various MDR proteins, such as P-gp and MDR-associated protein-1, and several pyrimidine-/quinazolinone-/nucleoside-based agents, such as azacitidine and gemcitabine, demonstrate high efficacy for a broad spectrum of cancers (Robak, 2011; Patil, 2018; He et al., 2020). This evidence concerns the gene PGP and cancer.