Absence of bidirectional regulation of α-chimaerin protein expression by age and dark rearing in mouse frontal cortex. A. Western blots showing levels of α1-and α2-chimaerin and actin protein expression in mouse frontal cortex. B and C. Mean levels of α-chimaerin isoform expression as determined by densitometry from three independent groups of mice. Means +/- S.E. are plotted. Data from each group were normalized against N9.5 animals.