Figure S1. IC50 decreased after APE1 knockdown. Figure S2. MMS increased colocalization of APE1 and FACT complex. Figure S3. FACT knockdown did not affect total APE1 level but decreased the occupancy of APE1 to p21 and DTL promoters. Figure S4. CBL0137 had minimal toxicity on cells. Figure S5. Combination of 5-FU and curaxins significantly inhibited xenograft growth. Figure S6. High expression of AcAPE1 and SSRP1 was observed in dMMR patients.