In addition, the atRBC NHE1 homolog (atNHE1) is 79% identical to human NHE1 at the amino acid level, retains the hallmark housekeeping characteristics of mammalian NHE1: cell pH and volume regulation, and is expressed in abundance in atRBCs compared to cell types known to over-express NHE1 (e.g., tumor cells) [33], [34]. The gene discussed is SLC9A1; the disease is neoplasm.