Fig. 1. S1 fiber formation in ARL cells at various states of confluency. ARL cells were cultured at a low cell density for 3 days (A) or in a confluent state for 3 weeks (B), and stained with anti-S1 protein antibody McAb 351 (A1, B1), monoclonal anti-vimentin antibody V9 (B2), or double-stained with McAb 351 (A2) and a polyclonal anti-vimentin antibody (A3). At low cell densities, S1 proteins are present not only in the nucleus, but also in the cytoplasm in association with VFs. (C) ARL cells were cultured for 3 days to 40% confluency (lane 1) and for 2 weeks at a full confluency (lane 2). Total proteins equivalent to 0.2 µg cellular DNA were analyzed by immunoblotting using McAb 351. Lane 3, reference S1 proteins isolated from rat liver nuclei. Bar, 25 µm.