Positive correlation between hPTTG1, CXCR2, and p21 expression in human breast invasive ductal carcinomas (IDCs). (A) The expression pattern of hPTTG1, CXCR2, and p21 in representative tumor tissues of patients with breast IDC were immunohistochemically analyzed. Tissues were scored as having strong (3+), moderate (2+) or weak expression (1+/0+). The criteria are described in the Materials and methods. Original magnification, ×400. Scale bars, 25 μm. (B-D) The expression data for hPTTG1, CXCR2, and p21 in 100 IDC specimens. The correlation between the indicated proteins was analyzed by using the Pearson χ2 test. (E) The expression data for p21 in 84 IDC specimens in which hPTTG1 expression was relevant to CXCR2 expression (the 84 specimens are marked with boxes in (B). (F) The expression data of hPTTG1 and CXCR2 in 50 primary IDC specimens and 50 matched metastatic carcinomas (upper panel). The specimens were classified into four groups: hPTTG1(2+,3+)/CXCR2(2+,3+), hPTTG1(2+,3+)/CXCR2(1+,0+), hPTTG1(1+,0+)/CXCR2(2+,3+), and hPTTG1(1+,0+)/CXCR2(1+,0+). The percentage of hPTTG1/CXCR2-stained specimens of each group is indicated in the lower panel. (G) The expression pattern of hPTTG1 and CXCR2 in representative breast IDC and matched metastatic lymph nodes (LNs). Original magnification, ×400. Scale bars, 25 μm. (H) MDA-MB-231 cells were stained with FITC-conjugated anti-CXCR2 or isotype control IgG for FACS analysis. (I) Cell lysates of MDA-MB-231, MCF-7, and MCF-10A cells were collected for immunoblot analysis. (J) MDA-MB-231 cells were plated for senescence assays. The percentage of positively stained cells is presented as the mean ± SEM (n = 3).