SAA1 and breast cancer: Using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assays, we observed that treatment with SAA1, SAA2, or THBS4 significantly promoted cell proliferation in three HER2+ mammary tumor cell lines derived from our mouse model, with effects evident on days 1, 2, or 3 (Fig. 4c).