DEFINITION of 'Commercial'. Relating to commerce. In the investment field, the term commercial is generally used to refer to a trading entity engaged in business activities that are hedged by positions in the futures or options markets.
The melanocortin 1 receptor controls which type of melanin is produced by melanocytes. When the receptor is activated, it triggers a series of chemical reactions inside melanocytes that stimulate these cells to make eumelanin. If the receptor is not activated or is blocked, melanocytes make pheomelanin instead of eumelanin.
They are located in the stratum basale, but branch out between the keratinocytes in suprabasal layers. About 5-10 % of the cells in the epidermis are melanocytes. The main purpose of melanocytes is the production of melanin, the protein responsible for the pigmentation of the skin, eyes, and hair. Melanin protects the cells in the skin and in deeper layers from the hazardous effects of UV radiation.