Fig. 2. (A) Superoxide dismutase protein (SOD) concentration measured as optical density (relative units) of immunoblots of sea urchin (Strongylocentrotus droebachiensis) embryos exposed to UVR in the five treatment groups. (B) p53 protein concentration measured as optical density of immunoblots of sea urchin (Strongylocentrotus droebachiensis) embryos exposed to UVR at five different wavelengths (treatment groups). (C) p21 protein concentration measured as optical density of immunoblots of sea urchin (Strongylocentrotus droebachiensis) embryos exposed to UVR in the five treatment groups. (D) cdc2 protein concentration measured as optical density of immunoblots of sea urchin (Strongylocentrotus droebachiensis) freshly fertilized embryos exposed to UVR in the five treatment groups. See representative immunoblot above each bar graph. N=3 samples for each treatment (i.e. filter); values are means ± S.D. of relative optical density. Treatment groups that share superscripts are not significantly different from one another using multiple comparison testing (SNK) at a significance level of 0.05%. FFE, freshly fertilized embryos.