Figure 4: Effect of the co-culture timing on the albumin secretion activity of hepatocytes on micropatterned mono-culture (open circles), micropatterned co-culture inoculated on day 1 (closed circles), micropatterned co-culture inoculated on day 3 (closed squares), and micropatterned co-culture inoculated on day 5 (open squares) of culture. Error bars represent SD. *, p < 0.05, compared with the value of mono-culture. #, p < 0.05, compared with the value of co-culture at day 5. +, p < 0.05, compared with the value of co-culture at day 3.