Representative MSP analysis of the four SFRP genes in MPN patient samples. DNA from Raji cells and water served as controls. Lane U, amplified product with primers recognizing unmethylated SFRP-1, -2, -4, and -5 sequences. Lane M, amplified product with primers recognizing methylated SFRP-1, -2, -4, and -5 sequences. Patient sample #1546 methylated at the SFRP-2 promoter, patient sample #1376 methylated at the SFRP-1 promoter.