Lamins constitute the nuclear lamina, which underlie the inner membran
e of the cell nucleus. Phosphorylation of lamins is a key factor in th
e regulation of nuclear structure during the cell cycle and of gene tr
anscription. Since an uncontrolled cell cycle and altered gene transcr
iption are major characteristics of neoplasms, we looked for differenc
es in lamin B-2 phosphorylation between PBMC, ALL and AML cells. Using
different lamin B-2-specific antibodies, we detected two different la
min B-2 species termed lamin B-2 and B-2A?. Although phosphorylation o
f lamin B-2 in leukemic cells was reminiscent of resting cells, the ma
jority of ALL and AML samples showed significantly higher and more alt
ered lamin B-2A phosphorylation compared to PBMC. It remains to be elu
cidated which mechanism leads to these alterations and whether it coul
d explain the extended G(1)-phase frequently observed in ALL cells. (C
) 1997 Elsevier Science Ltd.