SPOP (speckle-type POZ protein), also known as TEF2, is a member of the Tdpoz family containing one N-terminal MATH (Meprin and TRAF homology) domain and one C-terminal BTB/POZ domain. This protein inhibits IPF1/PDX1 transactivation of established target promoters, such as insulin, may be by recruiting a repressor complex. Through an interaction with CUL-3, SPOP is involved in ubiquitinylation and protein degradation. Recombinant human SPOP protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.