Identification of the C/EBP proteins that interact with APRE oligonucleotide to form C1, C2, C3, C4, and C5 complexes in livers of aged mice in response to LPS. The C1–C3, C4, and C5 complexes formed with control or LPS-treated (6 h) nuclear extracts from 28-mo-old C57BL/6 mice were resolved by preparative EMSA. The bands were excised from the gel, eluted, concentrated, and subjected to Southwestern blot and to ECL-Western immunoblot analyses as described in Ref. 3. (A) Southwestern analysis of liver nuclear proteins from 28-mo-old mice that form the C1–C3, C3, C4, and C5 DNA–protein complexes with the APRE oligonucleotide. Lane 1, control NE; lane 2, LPS-treated NE; lane 3, C1–C3 complexes formed with control NE; lane 4, C4 complex formed with control NE. Lanes 5 and 6, C3 and C4 complexes, respectively, formed with mouse liver NE after 6 h of LPS treatment. Lane 7, C5 complex 6 h after LPS treatment. (B and C) Western blot analysis using anti-C/EBPα and anti-C/EBPβ and the same nuclear extracts and complexes as in A.