MMP9 and keloid: Paltatzidou et al. (2017) assessed the expression of MMP-9 in the lesional skin biopsies taken from patients who received 5-fluorouracil treatment with skin keloids. They found that MMP - 9 was strongly expressed in the multinuclear giant cells of keloid biopsies, while it was significantly decreased after adding cryotherapy (P < 0.05).