In conclusion, our study confirmed the previously shown involvement of OCT1-3 and OATP1A2 as well as P-gp and BCRP in the complex net uptake of doxorubicin into cells involved in its desired pharmacological action (e.g., breast cancer cells) and toxicity (e.g., cardiomyocytes). Here, SLCO1A2 is linked to breast carcinoma.