Modification of lipophilic proteins in Friend erythroleukemia cells during their differentiation

In mouse erythroleukemia cells (MELC) a lipophilic protein of apparent M.W. 9.5 kdaltons increases during differentiation. This increase is due either to an increase of biosynthesis or to a structural alteration impairing the capacity of the protein to form polymers of apparent high M.W. or favoring its extractability. The increases is related to differentiation and precedes hemoglobin synthesis by at least 1 day. It is not related to virus production because it occurs in cells (line F 4-1) which do not produce virus, but it does not occur in cells (TFA-II) in which dimethylsulfoxide (DMSO) causes an increase in virus production. As it occurs in cells treated with 4 different inducers, and as the increase is less marked when antagonists of the inducers are also present, it is unlikely that the increase of the 9.5 Kdalton protein is due to an effect of the inducers unrelated to differentiation.