Fig. 2

Effects of different forms of iron, supplied to Caco-2 cell monolayers via either the apical or basolateral surface, on intracellular ferritin levels. Values indicate ferritin concentrations determined in extracts derived from Caco-2 cell monolayers that had been established over 2 weeks following seeding in bicameral chambers before being swapped for one further week (days 14–21 following cell seeding) into medium prepared with metal-depleted FBS only (Control), medium prepared with metal-depleted FBS plus 30 μM holo-Tf added to the medium only on the basolateral side of the cells (30 μM holo-Tf) or medium prepared with metal-depleted FBS plus ferric NTA (FeNTA) at 2 or 10 μM added to the medium only on the apical side of the cells. The bars and error bars indicate mean values + SD (n = 8 comprised of 4 replicate wells for each treatment from each of two separate plates set up in parallel). Data were compared by one-way ANOVA with Tukey’s post hoc test. Asterisks indicate statistically significant differences between treatments (*p < 0.05 and ****p < 0.0001)