The frozen tissues were thawed on ice and lysed in buffer (0.05 M Tris–HCl, 0.005 M mgCl2, 0.1 M NaCl, 1% Chaps (w/v), pH 7.0 [32]). The homogenized samples were centrifuged at 16,100g for 2 min at 4 °C. The supernatants were transferred to fresh tubes and used as hPAP stock. HPAP activity in each sample was determined by using a commercial kit (Phospha-Light system). Briefly, the protein concentration in each sample was measured using the BCA assay. One hundred microliters of protein (300 μg) was diluted with an equal volume of 1× assay buffer and incubated at 65 °C for 30 min to inactivate any endogenous alkaline phosphatase activity. The heated samples were then cooled on ice to room temperature and dispensed into 96-well plates (50 μl/well). Fifty microliters of assay buffer (room temperature) was added to each well and incubated for 5 min before addition of reaction buffer (50 μl/well, room temperature). The reaction was incubated for another 20 min and detected for luminescence (0.25 s/well).