PHC3 and neoplasm: To delineate the basis for the repressive effect of B9/B9L-ΔHD1 on primary tumor growth, we monitored potential changes in tumor cell proliferation and in tumor cell apoptosis by quantification of immunofluorescence staining for the mitosis marker phospho-histone 3 (PH3) and for the early apoptosis marker cleaved Caspase-3 (clCasp3), respectively (Supplementary Fig. 4A, B).