Immunohistochemical analysis of cyclin D1 in 48 MMs. (A) Representative case of MM group 1 showing strong, homogenous, cyclin D1 nuclear staining in the majority of tumor cells (> 80%, +++). Immunoperoxidase staining; original magnification × 400. (B) A representative case with intermediate cyclin D1 protein expression (++). Nuclear positivity is detected in 20% to 50% of the tumor cells. Note that the intensity of the staining varies from cell to cell. Immunoperoxidase staining; original magnification × 400. (C) MM with nuclear positivity in 10% to 20% of tumor cells (+) representing low levels of protein expression. Immunoperoxidase staining; original magnification × 640. (D) MM negative for cyclin D1. Note the positivity in endothelial cells used as internal control. Immunoperoxidase staining; original magnification × 640.