Table 2 The three MDCK strains that are most commonly used to study epithelial cell polarity

MDCK (NBL-2)

Parental MDCK cell line from which type I and II are derived. A heterogeneous population of epithelial cells that will form a polarised monolayer. The heterogeneity makes it possible that manipulation might select a sub-population, potentially complicating analysis of experiments.

ATCC, ECACC, JCRB

MDCK I

Derived from low passage parental cell line (NBL-2). Type I cells display high TER values (> 1000 Ω•cm²), are negative for the tight junction claudin-2, and reported to display an adrenalin, vasopressin and prostoglandin E sensitive adenyl cyclise, unlike type II cells. Have gap junctions. The ECACC report that they may display an unstable epithelial phenotype.

ECACC (ATCC and JCRB do not supply)

MDCK II

Isolated from high passage parental cell line (NBL-2). Type II cells display low TER values (~100 Ω•cm²) and are positive for claudin-2. They are larger and taller than MDCK I cells and lack gap junctions unless modified. MDCK II cells are the most commonly used MDCK strain and we would recommended them for most studies. Not to be confused with MDCK.2 strain sold by ATCC.

ECACC (ATCC and JCRB do not supply)