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). The gene discussed is SLCO1A2; the disease is breast cancer.