SP1 and Hyperoxaluria: As shown in the scheme summarized in Figure 10, hyperoxaluria, either induced by feeding rats a HP diet in vivo or via direct oxalate treatment in renal tubular cells in vitro, suppresses H2S formation by lowering Sp1 activity and its downstream effect on the expression of H2S-producing enzymes such as CBS, CSE, and 3-MST, at both the mRNA and protein levels.