Corrections and clarifications.
In the report "Transcription factor loading on the MMTV promoter: A biomodal mechanism for promoter activation" by T. K. Archer et al. (20 Mar., p. 1573), the sentence in the legend to figure 2 (p. 1574) which indicated treatment or lack of treatment with hormone should have read, "Samples in lanes 1, 2, 5, and 7 represent DNA from untreated cells, and samples in lanes 3, 4, 6, and 8 represent DNA from cells treated with hormone."