Growth factors are local regulators that: are produced by the anterior pituitary are produced by the anterior pituitary are modified fatty acides that stimulate bone and cartilage growth are modified fatty acides that stimulate bone and cartilage growth are found on the surface of cancer cells and stimulate growth and deelopment of target cells. are found on the surface of cancer cells and stimulate growth and deelopment of target cells. convey messages between nerve cells. convey messages between nerve cells. bind to cell-cell receptors and stimulate growth and development of target cells.