Immunofluorescence with mouse anti-alpha-tubulin was employed to visualize details of the microtubule network in a log phase monolayer culture of HeLa adenocarcinoma cells (presented above). The secondary antibody (goat anti-mouse IgG) was conjugated to Alexa Fluor 488 and mixed with Alexa Fluor 546 conjugated to phalloidin to simultaneously image tubulin and the actin cytoskeleton. Nuclei were counterstained with TO-PRO-3, a carbocyanine monomer with long-wavelength red fluorescence. Images were recorded with a 60x oil immersion objective using a zoom factor of 2.0 and sequential scanning with the 488-nanometer spectral line of an argon-ion laser, the 543-nanometer line from a green helium-neon laser, and the 633-nanometer line of a red helium-neon laser. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles, with the exception of Alexa Fluor 546, which was pseudocolored blue.