Protein expression studies are to a similar extent often aimed at identifying changes occurring in late melanoma development stages; recently, it was found that 6.1% of dysplastic naevi nuclei versus 1.2% of normal, benign naevi nuclei stained positive for minichromosome maintenance (MCM) protein 2, a polypeptide belonging to the MCM family of proteins that are involved in DNA replication and are assumed to be prognostically useful as cell proliferation marker similar to Ki-67 [22]. This evidence concerns the gene MKI67 and melanoma.