Cancer cell division. Immunofluorescent light micrograph of a cancer cell during the prometaphase of cell division (mitosis). During this phase, the nuclear envelope breaks and the microtubules (red) can attach themselves to DNA- containing chromosomes (green/yellow). Actin microfilaments (blue) make up the cell's cytoskeleton. Immunofluorescence uses antibodies to attach fluorescent dyes to specific cell tissues.