Fig. 4 . Caspase 3 and caspase 6 immunostaining. Immunostaining of the anterior region of secondary lens fiber cells (A) in wild-type (B,D,F,H) and DKO (C,E,G,I) lenses with anti-active caspase 3 (B,C) and anti-caspase 6 (F,G) antibodies. In negative controls (D,E,H,I), primary antibodies were omitted and only the secondary anti-rabbit IgG antibody, conjugated with Alexa Fluor 488, was used. (J) Image-Pro Plus v.5.1 software was used to quantitate fluorescence intensity in sections of lens from wild-type and DKO mice. Scale bar: 25 µm.