Immunohistochemistry of cyclin B1 and cyclin A. Examples of follicular lymphomas with high and low expression of cyclin A and cyclin B1. (Left) Tumor from patient no. 9 showing low fractions of cyclin B1-positive cells (magnification, × 200) and cyclin A-positive cells (magnification, × 600). Inserts show regions with higher expression, so called hot spots (magnifications, × 600 and × 100). (Right) Tumor from patient no. 55 with high percentages of cyclin B1-positive cells (magnification, × 400) and cyclin A-positive cells (magnification, × 200). Original magnifications, × 200 (top left panel and inset; bottom right panel); × 400 (top right panel; bottom left panel and inset). A Nikon Optishot microscope equipped with 20 ×/0.40 and 40 ×/0.65 objective lenses (Nikon, Tokyo, Japan) was used to visualize images. Pictures were taken with a Nikon CoolPix 990 camera, and Adobe Photoshop 6.0 software was used to zoom images to their present magnitude (Adobe, San Jose, CA).