Confirmation of cDNA microarray results of downregulated genes by RT-PCR. Five genes, exonuclease 1 (EXO1), ABC, sub-family F (GCN20), member 2 (ABCF2), MRE11 meiotic recombination 11 homolog A (MRE11A), topoisomerase (DNA) I (TOP1), and FK506 binding protein 12-rapamycin associated protein 1 (FRAP1), were analyzed by RT-PCR with total RNA from control and amygdalin (5 mg/mL, 24 h)-treated human colon cancer cells. As an internal control, CYCLOPHILN was amplified.