CA9 and neoplasm: Distributions of pHLIP peptides within tumors and their correlation with a variety of markers of tumor aggressiveness and invasiveness including CAIX, lactate dehydrogenase (LDH), Ki67 nuclear protein, and matrix metalloproteinases 7 (MMP7) have been demonstrated (Adochite et al., 2014; Rohani et al., 2019).