Fig. 1

Cytotoxic effects of EGCG on HaCaT cells were greater for the proliferation stage. HaCaT cells were cultured with DMEM containing indicated amount calcium for 72 h. The proliferative and differentiation stages were examined by western blotting analysis which antibodies against (a) involucrin (differentiation marker) and (b) cytoskeleton 5 (proliferation marker) with HuR and β-actin as a control, respectively. HaCaT cells were cultured in calcium free (proliferation stage, open squares) and 1.8 mM calcium (differentiation stage, filled squares) for 24 h. The cells were subject to the cell viability assay in three independent experiments. c The cytotoxic effects of EGCG were only apparent in the proliferative stage. d In contrast, the epidermal growth factor receptor kinase inhibitor AG1478 showed similar effects with both stages. Data (c and d) are presented as mean ± SD (n = 3). ** p < 0.01; *** p < 0.001 versus untreated cells