Recognizes the ribosomal RNA gene promoter and activates transcription mediated by RNA polymerase I through cooperative interactions with the transcription factor SL1/TIF-IB complex. It binds specifically to the upstream control element (By similarity). Homodimer (PubMed:10099786). Interacts with TBP (By similarity). Interacts with TAF1A (By similarity). Interacts with PHF6 (By similarity). Interacts with CEBPA (isoform 1 and isoform 4) (PubMed:20075868). Interacts with DDX11 (By similarity). Interacts with NOP53 (By similarity). Interacts with RASL11A (By similarity). Interacts with DHX33 (By similarity). Binds to IRS1 and PIK3CA (By similarity). Interacts with ALKBH2. Phosphorylated and activated by PIK3CA.