As outlined previously, published accounts vary in the degree of STAT5a positivity reported in human breast cancer, with one study indicating a 17% positivity rate for STAT5a in breast cancers (Nevalainen et al. 2004) (approximating the rate found in our article), and another demonstrating STAT5a in 76% (Cotarla et al. 2004). Here, STAT5A is linked to breast cancer.