CXCL8 and neoplasm: Recently, PPARβ/δ activators (L165041 and GW501516) were shown to induce interleukin 8 (Il-8) expression in endothelial cells by transcriptional and posttranscriptional mechanisms [97], and enhanced production of IL-8 due to PPARβ/δ activation caused not only elevated tumor angiogenesis, but also metastasis formation in vivo [98].