HP and renal cell carcinoma: It is therefore possible that in CC-RCC cells the binding of SMADs to the PAX2 promoter interferes with factors transcriptionally activating the promoter, which then leads to suppression of promoter activation, similar to the suppression of C/EBPβ- and STAT3-mediated transcriptional activation of the haptoglobin promoter by SMAD proteins, which has previously been reported [51].