CYP26B1 and infarction: Further, we hypothesize that 5ML, by up-regulating CYP26B1 expression and CYP26B1 activity may reduce retinoic acid levels in the infarction area; that reduced retinoic acid levels lead to a reduction of pro-differentiation pressure in the tissue; and that a reduction of differentiation pressure leads to the activation of angiogenesis.