CAMP and rosacea: TLR2 expression is found in the plasma membranes of a variety of cells in the skin including keratinocytes, mast cells, and endothelial cells.12 TLR2 expression has been found to be elevated in the skin of rosacea patients.13 Activation of TLR2 leads to the production of cathelicidin (LL-37) and cytokines in the pro-inflammatory cathelicidins pathway are described in more detail in this article.