Expression of the C/EBPα-ER fusion protein in line 10-αER cells.

Western blot analysis using a polyclonal antibody recognizing C/EBPα was used to detect endogenous C/EBPα or transfected C/EBPα fusion proteins. Lane 1: A U937 line transfected with a metallothionein promoter C/EBPα construct4 as a positive control; lanes 2-4: lysates from fetal liver cells of C/EBPα^−/− and C/EBPα^+/− animals; lane 5: the 10α-1αER line in which a C/EBPα-ER fusion protein7 has been stably transfected; lane 6: the 13α^−/− line. Shown on the right side are apparent molecular weight standards and, on the left, the position of migration of the C/EBPα-ER fusion and endogenous C/EBPα proteins. A number of smaller cross-reacting bands are observed in 10α-1αER; this has been observed previously in lines expressing this plasmid.7 9