HIF1A and neoplasm: To test this idea, we analyzed the expression levels of HIF1α and OATP1B3, a representative member of OATP family, in PDX-derived tumor tissues, and found high expression of both proteins, with HIF1α and OATP1B3 expressed in the nucleus and cytoplasm of tumor cells respectively in all 3 PDX samples (Figure 4A).