Identification of nuclear factor of activated T cells (NFAT) isoforms in the medullary thick ascending limb of Henle's loop (mTAL). A: total RNA quality and size were assessed by separation on a 1% agarose gel stained with ethidium bromide. Two distinct 28S and 18S ribosomal RNA bands were observed, and an intensity of 28S was twice that of 18S band with no degradation. Lanes 1–3: total RNA from mouse primary mTAL cells, mTAL tubules, and outer medulla. B: cDNA fragments for NFAT1-5 were generated by RT-PCR using total RNA from mouse mTAL cells. Possible contamination was ruled out by including PCR control samples with no DNA as a template. M, markers; 1–5, NFAT isoforms. C: DNA sequence analysis of NFAT5 cDNA fragment from mTAL cells.