Ware et al. (2014) on our recently published article “The Need for Human Breast Cancer Resistance Protein Substrate and Inhibition Evaluation in

et al., 2014). The relevance of breast cancer resistance protein (BCRP) in drug discovery and development is clearly an important topic and we are pleased to see that our article raises further interest and discussion. In our article, we primarily focused on a number of key aspects around the in vitro assessment of BCRP interactions (substrate and inhibition), supported by our own data. In the Discussion, we then aimed to put the in vitro results into context with in vivo data for BCRP-mediated interactions. For the latter purpose, an extensive survey of the literature was conducted and the relevant information currently available for BCRP-mediated interactions was summarized in our Table 1 (Poirier et al, 2014). It should be noted that in addition to sulfasalazine, we reviewed 13 other BCRP substrates to put the in vitro BCRP results into context and to see an overall picture of its clinical relevance—the main focus of our article. Furthermore, we wanted to highlight that BCRP-mediated drug-drug interactions (DDIs), as for other transporters, ca