<p>mRNA expression was studied by real-time PCR using TaqMan chemistry. ΔCt represents the difference between the Ct of a given gene and of the endogenous control (geometric mean of the Ct values of the selected housekeeping genes glyceraldehyde-3-phosphate dehydrogenase and hypoxanthine guanine phosphoribosyl-transferase, 21.887±0.296). Ct, cycle threshold.</p