Fig. 4.

Dkk1 inhibits esophageal epithelial cell proliferation. A: [³H]thymidine uptake assay in EPC1 and EPC2 cells following treatment with recombinant human Dkk1 (rhDkk1). Cells were pulsed for 24 h with 1 μCi/ml [³H]thymidine. Values are means ± SE of 3 independent experiments. *P ≤ 0.05 vs. untreated. B: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay following treatment with 100 and 500 ng/ml rhDkk1 in EPC1 and EPC2 cells. Values are means ± SE of 3 biological replicates performed in sextuplicate and presented as percentage of untreated controls on day 0. *P ≤ 0.05, untreated vs. 100 ng/ml rhDkk1; #P ≤ 0.05, untreated vs. 500 ng/ml rhDkk1. C: immunofluorescence staining of Ki-67 in EPC2 cells following treatment with 500 ng/ml rhDkk1 for 48 h. LI, labeling index. Values are means ± SE of 3 independent experiments. *P ≤ 0.05. D: MTT assay following treatment with anti-Dkk1 Ab or human IgG in EPC2 cells. Values are means ± SE of 3 experiments performed in triplicate and presented as percentage of untreated controls on day 0. *P ≤ 0.05 vs. untreated and human IgG.