Wondering how these incredible growth-stimulating proteins are transferred to a moisturizer or serum? Frank says that there are skin-derived options from a human source or bioengineered EGF products, sometimes from trick plant cells. Celebrity facialist and founder of Joanna Vargas Salons and Skin Care, Joanna Vargas, says that the peptides or protein chains are developed specifically to speed up wound healing at a cellular level.

"We have EGF in our skin to help repair and replicate existing cells," says Vargas. "EGF in skin care is meant to stimulate the same type of function in order to rejuvenate the skin and increase collagen production."

Growth factors are often found in serums and masks, but they are also in face and eye creams.

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King says that plant versions are bioengineered in a lab and can be barely-grown EGFs, such as those found in Bioeffect and DNAEGF Renewal. Vargas sources EGF from fruits and vegetables for her product line.

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Hadley says that the human stem cells can come from any source. And we mean any source. In fact, this is where the "penis facial" got its nickname: Georgia Louise's Hollywood EGF facial reportedly uses EGF derived from cells from the removed foreskin of newborn Korean babies (yes, really).

SkinMedica also uses epidermal growth factors in its products. They're derived from several different human cells grown in a laboratory, including skin cells, bone marrow stem cells and fat stem cells. The growth factors can even be extracted from a person's blood, or platelet rich plasma (PRP).

King says that the SkinMedica TNS Recovery Complex, $179, specifically contains proteins derived from the fibroblasts of neonatal foreskin.

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King says that growth factors have been of particular interest for topical products because of their ability to promote wound and ulcer healing when applied topically. One study highlighted how a serum containing recombinant EGF showed significant improvement to brown spots, skin texture, pore size, red spots and wrinkles, when applied twice daily over a three-month period. (Schouest JM, Liu TK, May RL. J Drugs Dermatol. 2012; 11(5): 613-620.)

Their wound-healing ability makes EGF products perfect after laser treatments, according to Vargas. The laser is meant to stimulate collagen production. This collagen boost combined with wound-healing EGF has a transformative effect. Similarly, Vargas adds that growth factors are helpful for repairing sun damage and skin mutations from environmental stress.

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The experts agree that growth factors are suitable for all skin types, although King explains they are targeted for aging skin.

Frank adds that EGFs don't cause sun sensitivity. (Of course, that's not a free pass to skip sunscreen!) Also, unlike some ingredients, Frank says that growth factors can be used in conjunction with other antioxidant or retinoid products to improve skin quality, thickness and health.

Image via Imaxtree