M-1

M-1 cells are derived from the normal kidney tissue of tg(SV40E)Bri7 transgenic mice and contain integrated SV40 viral DNA. They keep some common characteristics with the cells of the cortical collecting duct (CCD), including typical morphology and expression of CCD-specific antigens. Otherwise, most M-1 cells exhibit features of either intercalated cells or principal cells, the two major cell types of the cortical collecting duct. A subset of 5–10% of the population displays a mixed phenotype, expressing markers of both cell types. When cultured on permeable supports, M-1 cells are capable of forming cavity-like structures and exhibit a measurable negative transepithelial potential difference, indicative of functional polarization.