The pharmacological relevance of the combination (LX2931 and gemcitabine) was assessed by IHC measurement of the expression of the hypoxia marker, carbonic anhydrase IX (CA IX) [44], in tumor tissues obtained from mice harboring PDXs of pancreatic cancer treated with gemcitabine or with the combination of gemcitabine and LX2931 (Figure 5). Here, CA9 is linked to pancreatic neoplasm.