HBEGF and psoriasis: For example, we observed decreased accessibility in regulatory elements associated with the genes that encodes Elovl1, involved in epidermal barrier formation (20), Cdc20, an essential regulator of cell division, Tgm3, a transglutaminase involved in the formation of the cornified cell envelope upregulated in psoriasis (21), Hbegf (encoding one of the EGFR ligands) (Figure 6B).