CIAO1 is a essential component of the cytosolic iron-sulfur (Fe/S) protein assembly machinery. It is a multiprotein complex that mediates the incorporation of iron-sulfur cluster into extramitochondrial Fe/S proteins. CIAO1 seems to specifically modulate the transactivation activity of WT1 and may function to regulate the physiological functions of WT1 in cell growth and differentiation. As part of the mitotic spindle-associated MMXD complex, it may play a role in chromosome segregation.