To analyze the effect of OR-2003 and OR-2100 on DNA demethylation, we first analyzed the DNA methylation levels of (1) the marker region of our detection system, namely exogenous UCHL1 promoter (Additional file 1: Figure S2) and (2) a promoter CpG island of a gene frequently methylated in cancer cells, namely the OSR2 promoter CpG island, using quantitative MSP [18]. The gene discussed is OSR2; the disease is cancer.