Loss of high-molecular-weight proteins in liver microsomes of rats treated with hepatocarcinogens.

Microsomal preparations from rats treated with 2-acetylaminofluorene (2-AAF) or with 4-dimethylaminoazobenzene (4-DAB), alone or followed by phenobarbital (PB), showed almost complete loss of microsomal proteins of molecular weights higher than 60,000, as shown by Sephadex G-150 gel filtration technique. Induction of a number of microsomal proteins in the lower ranges of molecular weights was also recorded due to the treatment of these two hepatocarcinogens with and without the use of PB as a promoter. These modifications in the protein patterns of microsomes might be due to altered genetic expression resulting in uncontrolled cell division/cell cycle.