Component of a protein kinase signal transduction cascade. Mediates activation of the NF-kappa-B, AP1 and DDIT3 transcriptional regulators. {ECO:0000269|PubMed:12912994, ECO:0000269|PubMed:14661019, ECO:0000269|PubMed:14743216, ECO:0000269|PubMed:33729480, ECO:0000269|PubMed:33891857, ECO:0000269|PubMed:9006902}. This is the function of MAP3K3 (mitogen-activated protein kinase kinase kinase 3, Ensembl gene identifier ENSG00000198909).