NPM1 and neoplasm: The proteins that most frequently showed strong tumour cell immunoreactivity in primary colorectal cancer were NPM1 (99.6%), major vault protein (MVP, 81.1%) and prohibitin (PHB, 75.6%) while in lymph node metastasis those proteins which showed the most frequent strong tumour cell immunoreactivity were NPM1 (95.8%), MVP (74.5%) and heat shock protein 60 (HSP60, 63.9%) (Figure 4).