Expression of Ki67 in tumor xenografts was determined by fluorescent immunohistochemistry on frozen sections to examine the effect of G-1 on the proliferation of breast cancer cells in vivo (46 (link)). Fluorescent immunohistochemistry was also used to determine tubulin distribution and phosphorylated histone H3. Images were captured with a Zeiss 710 Meta Confocal Laser Scanning Microscope and analyzed with the Zeiss Zen 2010 software.