STAT3 and acute kidney injury: In a model of acute kidney injury induced by HgCl2, STAT3 activation in renal tissue has been linked to interleukin-6 (IL-6) signaling; because normal renal tissue does not express the IL-6 receptor, this activity has been linked to IL-6 trans-signaling, which involves signaling through a soluble form of the IL-6 receptor (34).