ABCG2 and breast cancer: It was demonstrated that the KISS1 receptor (KISS1R) regulated the expression of the drug efflux transporter BC resistance protein (BCRP), a crucial regulator of the multi-drug resistance phenotype in BC significantly elevated in TNBC, demonstrating that KISS1R-induced drug resistance was dependent on the activity of adenosine triphosphate-binding cassette (ABC) transporters [80].