MSP products of several hemimethylated or cellularly heterogeneous tumor tissues. Both 98 bp MSP product of the methylated APC promoter and 111 bp MSP product of the unmethylated promoter could be observed in tumor tissues. Lanes 1 and 3 represent the MSP products of tumor tissues by applying unmethylated primers. Lanes 2 and 4 show the MSP products for the same tissues using methylated primers. Lanes 5 and 6; negative control (blood) which results in 111 bp product. Lanes 7 and 8; positive control (universally methylated DNA) with a 98 bp product. M; molecular size marker 50 bp (Fermentase).