CYP26B1 mRNA in atherosclerotic lesions. Murine arterial biopsies from C57BI/6 (n = 6) and Apoe-deficient (n = 11) mice were analyzed by qPCR for Cyp26B1 mRNA (A). CYP26B1 mRNA levels were measured in human carotid artery biopsies cultured in the absence or presence of atRA (n = 6) (B). Values are mean ± standard error of the mean (SEM) of arbitrary units normalized to TATAbbp (mouse) or β-actin (human). **P < 0.01, *P < 0.05.