Fig. 6: USP4 protein is downregulated in human breast cancer and positively correlates with BRCA1.

a IHC staining of USP4 in normal human breast tissues. Breast lobules (left) and ducts(middle) were shown; negative control for IHC staining (right). Scale bar, 20 μm. b Correlation between BRCA1 and USP4 expression was compared. 90 cases of breast cancer tissues within different clinicopathological TNM stages were analyzed by IHC. Representative photographs of BRCA1 and USP4 immunoreactivity in breast cancers were shown. Normal adjacent breast tissues and paired cancer tissues with different TNM stage in a breast tissue microarray are shown in supplementary Fig. 6. Scale bar, 200 μm. c USP4 and BRCA1 protein levels in breast cancer tissues of different stages were quantified and presented as boxplots. Within each box, horizontal black lines denote median values, boxplots represent the interquartile range (25th to 75th percentile) and whiskers extend to the minimum and maximum values within 1.5 times the interquartile range. Data were analyzed by the χ² test. d Correlation analysis of USP4 and BRCA1 in breast cancer tissues. The χ² test was used for statistical analysis. Correlation coefficient, r = 0.5483, p < 0.0001. e Expression of USP4 and BRCA1 in human breast cancer cell lines. Breast cancer cell lines were analyzed by WB.