May play an important role in tumor biology. Interacts with PDZK1 (PubMed:9461128). Forms a heterodimer with SLC5A2; this interaction enhances SLC5A2 transporter activity over a hundred-fold (PubMed:34880493). Expressed at significant levels only in a single epithelial cell population, the proximal tubular epithelial cells of the kidney. Diffusely expressed in various carcinomas originating from kidney, colon, lung and breast.