Figure 1.

Detection of methylated RASSF2A promoter in the primary tumour (T), liver metastases (M) and plasma (P) from patients 1 and 2. For patient 2, T1 and T2 correspond to the right and left colon adenocarcinoma, respectively. Genomic DNA was modified by bisulphite treatment and amplified with primers specific of the methylated RASSF2A promoter. M, molecular marker; Un, unmethylated DNA used as a negative control; Met, methylated DNA, used as a positive control. The arrows indicate the 110 bp amplified product (A). Detection of a KRAS mutation in the plasma from patient 1. Two independent real-time PCRs were performed from DNA extracted from plasma, in the presence and in the absence of a PNA specific of the wild-type KRAS sequence. The presence of mutant DNA within the sample is detected by a significant shift towards lower values of the cycle threshold (C_t) when the PNA is added to the reaction. The upper and lower panels correspond to the sequences of the amplified products obtained in the absence and presence of the PNA, respectively. In the presence of the PNA, only the mutant allele is amplified. The sequences correspond to the antisense strand, the box marks codon 12 and the arrows the c.35G>C mutation (B).