Histone H3 binds to the αVα5 integrin and to the Mer receptor but not to the αVα3 integrin. The 96-well plates were precoated with histone H3 or BSA (1 μ g/mL) in PBS. The plates were then washed three times with PBS and blocked with PBS containing 1% BSA for 1 h. After removing the blocking solution, the plates were incubated with increasing doses (0, 0.1, 0.5, 1 and 5 [μg/mL) of recombinant mouse Mer (A), αVα5 (B) or αVα3 (C) dissolved in PBS for 1 h, followed by washing with PBS containing 0.05% Tween 20. Protein bound to the wells was quantified by solid-phase ELISA as described in Materials and Methods. A450, absorbance at 450 nm.