MIF and cyst: Here, we provide data showing that (i) MIF as well as its transporter protein ABCA1 are regulated by HIF-1α in cyst-lining cells in vivo and in vitro, (ii) that cAMP is also a regulator of MIF, and (iii) MIF induces cyst cell proliferation in vitro in a macrophage-independent way which can be inhibited by the MIF-inhibitor ISO-1.