Yongchao Dou et al. used three isogenic colorectal cancer cell lines that differ only in KRAS mutation status including DLD-1 (containing both wild-type and G13D mutant KRAS [KRAS proto-oncogene, GTPase] alleles and isogenically-matched derivative cell lines), DKO-1 (mutant KRAS allele only), and DKs-8 (wild-type KRAS allele only), and found that most circRNAs are down-regulated in KRAS mutated colorectal cancer cell lines. The gene discussed is KRAS; the disease is colorectal cancer.