Fig. 1. Changes in expression of lamins and LAP2 during myogenesis. Exponentially growing C2C12 myoblasts were induced to differentiate with 2% horse serum. Whole cell extracts were prepared at 0, 12, 18, 24, 36, 48, 72, 96 and 120 hour time points, and quantities were standardized to equal amounts of DNA as follows. Cell extracts were prepared at various time intervals and subjected to agarose-gel electrophoresis and stained with ethidium bromide. The genomic DNA was visualized as a slowly migrating band, separated from the faster migrating RNA specimens. To assure that detection was within a linear range, the extracts were analysed in serial dilutions. The intensity of bands corresponding to genomic DNA was analysed by densitometry using UVI bandmap software and the volume of each sample adjusted so that equal amounts of DNA were added to each lane of protein gels. Levels of expression of myogenin (a), lamin A (b), lamin B1 (c), lamin B2 (d), lamin C (e) and LAP2 (f) were analysed by western blotting and the intensity of each band evaluated by densitometry. The graphs below each blot are representative of three independent experiments.