Figure 2.

Expression of cortactin, FADD, and Chk1 in breast cancer cell lines and primary breast tumors. (a) Five human breast cancer cell lines were examined for cortactin, FADD, and Chk1 protein expression by Western blot and immunocytochemistry. Protein levels were equivalent between the two methods. (b) Tumor staining reveals cytoplasmic staining of cortactin and FADD, whereas Chk1 protein is mainly present in the nuclei. Staining intensity for cortactin and FADD was evaluated as negative (0) or low (1; left panels: cortactin low, FADD negative), intermediate (2; middle panels), and high (3; right panels). Chk1 staining was evaluated according to fraction positive nuclei (0% to 5% left panel, 6% to 50% middle panel, 51% to 100% right panel). In tumors with highly stained nuclei Chk1 was also present in the cytoplasm. Scale bar = 25 μm. Chk1, checkpoint kinase 1; FADD, Fas-associated death domain.