DNMT1 and lentivirus infection: To identify the genes that were differentially expressed upon inhibition of DNA methylation, we conducted microarray analyses of Apc-deficient intestinal tumor organoids after treatment with 1 μM 5-Aza-CdR and knockdown of Dnmt1. Total RNAs were extracted at 4 days after 1 μM 5-Aza-CdR treatment and at 9 days after the lentivirus infection, respectively.