Binds DNA specifically as homodimer or heterodimer with other PAR factors. Highly expressed in liver; lower levels in lung and kidney. Accumulates according to a robust circadian rhythm. A chromosomal aberration involving HLF is a cause of pre-B-cell acute lymphoblastic leukemia (B-ALL). Translocation t(17;19)(q22;p13.3) with TCF3. Belongs to the bZIP family. PAR subfamily.