STAT3 and breast cancer: In addition, in line with finding that DE-EDCP treatment markedly reduced expression of STAT3 at protein and mRNA level in vitro, immunohistochemistry analysis showed a similar trend for decreased percentage of Y705 phospho-STAT3-positive cells within breast cancer tissue of DE-EDCP treated mice compared to control group, although this difference did not reach statistical significance (Figure 7C and 7D).