Table 3.

Relationship between alkaline phosphatase activity and culture time of Caco-2 monolayer.

t/d	Ratio of alkaline phosphatase	Activity (U/g protein)
5	1.63 ± 0.09a	22.36 ± 2.32a
9	2.98 ± 0.25a	21.38 ± 2.64a
13	6.73 ± 0.58b	21.79 ± 2.83a
17	14.27 ± 1.35c	62.34 ± 5.58b
21	16.41 ± 0.79c	68.92 ± 6.47b

Alkaline phosphatase is a marker enzyme of the brush border differentiated during the formation of Caco-2 cell monolayer. Alkaline phosphatase activity can mark the degree of differentiation of cells to a certain extent. With the increase in culture time, alkaline phosphatase activity in the cells increases, and the cells form polar differentiation. Each value was represented as mean ± SD of three independent experiments (a < b < c < d, all p < 0.01).