Human T-cell leukemia virus enhancer factor (HTLF) may be a forkhead domain binding protein. It may function in the transcriptional regulation of the human T-cell leukemia virus long terminal repeat.Human T-cell leukemia virus enhancer factor (HTLF) may be a forkhead domain binding protein. It may function in the transcriptional regulation of the human T-cell leukemia virus long terminal repeat.