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.
The genetic control of skin color is based on a combination of specific hormones and specific receptors in the skin. The major receptor for the production of melanin is the melanocortin1 receptor (MC1R), of which there are five types. There are three major melanocyte-stimulating hormones that are produced by cells in the intermediate lobe of the pituitary gland.