SP1 and cardiac hypertrophy: Meng et al. (2016) reported that CSE expression is downregulated while KLF5 expression is elevated in hypertrophic myocardial tissue and Ang II-treated cardiomyocytes in hypertensive rats. Administration of GYY4137, an H2S donor, inhibited cardiac hypertrophy and downregulated KLF5 protein levels. H2S S-sulfhydrated Sp1 at Cys664 site, inhibiting Sp1 binding to the KLF5 promoter, thereby downregulating KLF5 transcription and preventing cardiac hypertrophy (Meng et al., 2016).