DKK3 and non-small cell lung carcinoma: Because DKKs and SFRPs have been documented to be downregulated by promoter hypermethylation in NSCLC, we used methylation-specific PCR (MSP) analysis to examine the methylation status in 50 fresh-frozen NSCLC tissue specimens and found that 23 cases and 21 cases displayed methylation in DKK3 and SFRP1 promoters, respectively, and that 27 cases and 29 cases exhibited unmethylated DKK3 and SFRP1 promoters, respectively.