Fig. 3. Detection of nSMase 1 in subnuclear fractions of AH7974 cells. (A) Neutral SMase activity in subnuclear fractions, such as nuclear envelope, chromatin, nuclear matrix, and denuded nucleus were measured. 10 µl aliquots of each sample (4 ml) were assayed for neutral SMase activity. Activities were relative to that in the intact nucleus, which was taken as 100%. (B) Western blotting of subnuclear fractions were carried out using the anti-rnSMase 1 antibody with aliquots of subnuclear fractions corresponding to 75 µg DNA, as indicated. Immunoreactive protein bands were detected at 47.6 kDa.