NKCC1 COOH-terminal domain contains a putative nucleolus localization signal. A and B: MDCK-WT (A) and MDCK transfected with NKCC1–239 COOH-terminal mutant (B) were cultured in MatTek glass bottom microwell dishes. Cells were stained with PureBlu Hoechst 33342 and imaged live. C: nucleolus predicted sequence and score. WT, wild-type; 239, Δ92aa. Bars = 20 μm. GFP, green fluorescent protein; MDCK, Madin-Darby canine kidney; NKCC1, Na+-K+-2Cl− cotransporter-1. The data are representative of more than 10 individual experiments and more than 50 images taken.