We have examined the expression of lamins A, B1, and C in human tissues and 
cancer cell lines and the function of the lamin A/C and B1 gene promoters in 
transfected cells. Northern analysis and immunoblotting demonstrated that lamin 
A/C mRNA and protein were not detectable in some human cell lines whereas lamin 
B1 was always present. Sequencing of approximately 2.6 kb of the lamin A/C and 
1.6 kb of the lamin B1 genes 5' to the translation initiation sites showed that 
they did not contain typical TATA boxes near the transcription start sites. The 
lamin B1 and A/C proximal promoter regions were transcribed in transfected HeLa, 
Raji, and NT2/D1 cell lines even if the cells did not contain detectable 
endogenous lamin A/C mRNA or protein. These results show that, similar to most 
cytoplasmic intermediate filament genes, transcriptional regulatory elements in 
the promoters of the human nuclear lamin A/C and B1 genes do not control their 
cell type-specific expression in culture lines.