We used immunofluorescence staining as a more sensitive technique to detect yH2AX changes, together with the previously established automated high-throughput microscopy [39] to improve accuracy for counting of yH2AX foci formation and to assess the level of DNA damage and repair ability in BRCA1-deficient and BRCA1-proficient mouse mammary tumor cells treated with GSK126 and AZD1390 (Fig. 5A, B). This evidence concerns the gene BRCA1 and breast cancer.