ERBB2 and neoplasm: To validate whether these three secretory proteins, SAA1, SAA2, and THBS4, can indeed promote HER2+ tumor development, we next examined the effects of the addition of each of the three synthesized peptides to the HER2+ mammary tumor cell culture derived from our MMTV-neu mouse cohorts, thereby confirming that these transcriptomic findings translate into functional drivers of tumor development in this model.