Acts as a transcriptional activator or repressor. Inhibits the transcriptional activation of Zic family proteins ZIC1, ZIC2 and ZIC3. Retains nuclear Zic proteins ZIC1, ZIC2 and ZIC3 in the cytoplasm. Modulates the expression from both cellular and viral promoters. Down-regulates Tat-dependent transcription of the human immunodeficiency virus type 1 (HIV-1) LTR by interacting with HIV-1 Tat and Rev and impairing their nuclear import, probably by rendering the NLS domains inaccessible to importin-beta. Also stimulates activation of human T-cell leukemia virus type I (HTLV-I) LTR. Binds to the axin complex, resulting in an increase in the level of free beta-catenin. Affects axin regulation of the WNT and JNK signaling pathways.