While DC2 readily achieve it under TGF-β1/GM-CSF alone conditions (13), Notch signaling, which is detected in LCH lesions (22), is an additional requirement for Langerin expression by monocytes (13, 20, 37, 38) and was recently implicated in the differentiation of normal epidermal LC (42). This evidence concerns the gene TGFB1 and Langerhans cell histiocytosis.