PLZF (promyelocytic leukemia zinc finger), also known as Zbtb16, Zinc finger and BTB domain-containing protein 16, Zfp145, is a member of the BTB-POZ family of transcription factors. It was first identified in a patient with acute promyelocytic leukemia, where a reciprocal chromosomal translocation t(11;17)(q23;q21) resulted in a fusion with RARA gene encoding retinoic acid receptor alpha. Expression of this transcriptional repressor in immune cells differs between human and mouse. In humans, PLZF is expressed in CD34+ progenitor cells and in primitive multipotent hematopoietic cell lines, NK cells, gamma/delta T cells, CD4+ and CD8+ T cells. It is also expressed in MR1-specific mucosal-associated invariant T cells as well as in MHC class II-restricted T cells that develop via a thymocyte-thymocyte interaction. PLZF is involved in NK cell function, cellular quiescence, and growth suppression. It also inhibits gene expression induced by retinoic acid receptor. In mice, PLZF is highly expressed in immature CD1d-resricted invariant NKT (iNKT) cells, a subset of gamma/delta (Vg1.1+Vd6.3+) T cells, and non-invariant CD1d-restricted T cells. PLZF exists as a homodimer or in complex with PLZP, and has been shown to be involved in the development of NKT cells. It is also reported to be expressed in embryonic tissues, giving rise to hematopoietic progenitors.