HMOX1 and neoplasm: Furthermore, these Res@AuNPs turned out to be effective in downregulating the enzymatic activity and/or expression of a panel of signaling targets involved in tumor progression and metastasis, such as MMP-9, cyclooxygenase-2 (COX-2), NF-κB, AP-1 (activator protein-1), PI3K/Akt (phosphatidylinositol 3-kinase/protein kinase B), and ERK, as well as in upregulating heme oxygenase-1 (HO-1) expression [93].