Definition of "growth factor" []

• A substance that affects the growth of a cell or an organism. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "“Pleiotrophin looks to be a unique growth factor that can cover long distances quickly,” says Hoke."
• "TGF beta-1 by Reviva is a growth factor shown to play a key role in skin cell nourishment uptake and construction."