IDH1 and cancer: Knockdown of NR4A1 decreases expression of several Sp1-regulated genes (but not Sp1) including survivin, bcl-2, EGFR, cyclin D1 and c-Myc in Rh30 and RD cells as observed in other cancer cell lines and in this study, ChIP assays indicated that not only survivin (Figure 4D) but also TXNDC5 and IDH1 are regulated by interactions of p300/NR4A1 with Sp1 bound to GC-rich promoters (Figure 1B).