Role of T cells, antigen-presenting cells, keratinocytes, Langerhans' cell, macrophages, natural killer cells, an array of Th1 type cytokines, certain growth factors like vascular endothelial growth factor (VEGF) keratinocyte growth factor (KGF) and others have been suggested to play a key role in pathogenesis of psoriasis. This evidence concerns the gene VEGFA and psoriasis.