FEN1, a structure-specific endonuclease with 5′-exonuclease and endonuclease activity,37 plays multiple roles in processing intermediates of Okazaki fragment maturation, telomere maintenance and stalled replication fork rescue.38 Generally enhanced expression of FEN1 in tumors may lead to chemoresistance.39–41 Our results indicated that FEN1 was highly expressed in CRC and the effect of MEIS1 on tumor growth and oxaliplatin reactivity depended on FEN1 suppression. This evidence concerns the gene FEN1 and colorectal carcinoma.