PCI Products › MLH1 Deficient Single control FFPE block Image 1 of 1 MLH1 Deficient Single control FFPE block $500.00 Single paraffin wax block / cell FFPE block.A single FFPE block is comprised of a single cell line plug selected for demonstrating MLH-1 protein expression. Add To Cart Added! Single paraffin wax block / cell FFPE block.A single FFPE block is comprised of a single cell line plug selected for demonstrating MLH-1 protein expression.