IHC directly evaluates the MMR protein presence/absence in the tumor cells while PCR-based tests use a set of primers (most commonly including two mononucleotide probes (BAT25 and BAT26) and three dinucleotide probes (D2S123, D5D346, D17S250)) to check for PCR products size differences between normal and tumor tissues (band-shift). This evidence concerns the gene MRC1 and neoplasm.