| − | **While most soluble mitogenic growth factors are made by one cell type to stimulate another ('''heterotypic signaling'''), cancer cells can synthesize the growth factors to which they are responsive - ''positive feedback loop'' or '''autocrine stimulation''' - and obviates dependence on GFs from other cells within the tissue.
| + | *While most soluble mitogenic growth factors are made by one cell type to stimulate another ('''heterotypic signaling'''), cancer cells can synthesize the growth factors to which they are responsive - ''positive feedback loop'' or '''autocrine stimulation''' - and obviates dependence on GFs from other cells within the tissue. |