Fig. 4. Changes in solubility properties of LAP2 during myogenesis. (a) C2C12 myoblast cultures were induced to differentiate and, after 0, 72 and 120 hours, cells were harvested and subjected to nuclear isolation. Nuclei were either solubilized in SDS (nuclei) or sequentially extracted with hypotonic (LS) or hypertonic (HS) buffer. Samples were resolved by SDS-PAGE along with material resistant to extraction (INS), transferred to nitrocellulose and blotted with antibodies against LAP2 and the intensity of each band evaluated by densitometry. (b) C2C12 myoblasts were grown on glass coverslips and induced to differentiate with 2% horse serum. After 0, 48, 72, 96 and 120 hours of differentiation, cells were fixed and immunostained with anti-lamin, anti-LAP2 and anti-myogenin antibodies, and observed using a confocal microscope. Arrows show postmitotic myoblasts and arrowheads show mitotic myoblasts. (c) 48-hour cultures of differentiating myoblasts were stained with anti-lamin C and LAP15 (anti-LAP2) antibodies. Bars, 10 µm.