Erratum: Viable offspring derived from fetal and adult mammalian cells

Nature 385, 810-813(1997). In this Letter in the 27 February issue, a production error led to the image for part b of Fig. 1 (fetal fibroblasts) being used twice, as parts b and c. The correct image for Fig. Ic (mammary-derived cells) is shown below, and is also on the Nature web site and in reprints.