Integrin α6β4 promotes DNA repair and cell survival in response to DNA damage. (A) Cells were treated with 500 μM H2O2 in fresh medium daily for 7 days. Each day cell proliferation was measured by MTT colorimetric assay. (B) Cells were exposed to 30 J/m2 UV light and DNA isolated at indicated time points. Slot blot assay was performed using antibody for 6-4 photoproducts and percent repair compared to damage achieved immediately after exposure (0 hr).