HSP90AA1 and neoplasm: Third, our wet lab validation indicated that silencing of the PSMG4 gene not only helped attenuate proliferation of tumor cells, but also significantly reduced the mRNA level of heat shock protein 90 (HSP90AA1) - a cytosolic protein that belongs to the HSP90 family, which was in agreement with the downstream signaling pathway predicted by MetaCore (Figure 9).