Cover photograph (Copyright © 1999, American Society for Microbiology. All rights reserved.): Rat1 cells expressing the E2F-1 transcription fractor fused to the ligand binding domain of the estrogen receptor were grown in the absence (left panels) or presence (right panels) of the synthetic estrogen receptor antagonist 4-hydroxytamoxifen (OHT). E2F-1 expression was monitored by immunofluorescence (red), and DNA was stained by 4',6-diamidino-2-phenylindole (blue). OHT causes the fusion protein to translocate from the cytoplasm to the nucleus. (See related article in the September 1999 issue: vol. 19, p. 6379.)