The role of NFAT5/TonEBP in establishing an optimal intracellular environment

NFAT5/TonEBP, the most recently described member of the rel/NFκB/NFAT family of signal-dependent transcription factors, is activated by extracellular hypertonicity—a cellular stress of particular and perhaps unique physiologic relevance to cells of the renal medulla. Accumulating evidence suggests that NFAT5/TonEBP also functions in vivo under isotonic conditions as part of a ubiquitous regulatory mechanism that senses and adjusts available intracellular volume during cell growth to establish an intracellular environment appropriate for optimal cell proliferation.