Prostate cancer. Immunofluorescent light micrograph of prostate cancer cells. The large cell nuclei, which contain DNA (deoxyribonucleic acid, dark blue), are typical of the rapid cell division that occurs in cancer. Proteins in the cytoplasm are green. One cell with red cytoplasm (upper right) is undergoing mitotic cell division. The centrioles (yellow) and spindle fibres (light blue) needed for division can be seen. Prostate cancer is one of the most common male cancers, mainly occurring in the elderly. Immunofluoresc- ence uses antibodies to attach fluorescent dyes to specific tissues and molecules within the cell. Magnification unknown.