In extracellular secreted form, promotes proliferation and activation of CD8+ T cells, suggesting a cytokine-like function (PubMed:25125657). Enhances cytotoxic anti-tumor activity of CD8+ T cells (PubMed:25125657). May inhibit ERK and JNK signaling activity (PubMed:18087676, PubMed:23070808). May suppress cell migration and invasion activity, via its effects on ERK and JNK signaling (PubMed:23070808). In the nucleus, enhances stability of the PCAF histone acetyltransferase (HAT) complex member TADA2A and thus promotes PCAF-mediated H3K14 and H4K8 HAT activity. May inhibit TADA2A-mediated TP53/p53 'Lys-321' acetylation, leading to reduced TP53 stability and transcriptional activity. May also promote TADA2A-mediated XRCC6 acetylation thus facilitating cell apoptosis in response to DNA damage.