Photograph comparing tumor growth of E11 and its derivatives in nude mice. Pictures were taken 20 days postinjection with the indicated cell type. Cell lines: E11, H5ts125-transformed primary rat embryo cell line showing the non-progressed localized tumor phenotype; E11-NMT, nude mouse tumor-derived E11 clone, showing the progressed aggressive transformed phenotype; E11/PEG-3 S, a clone of E11 cells stably overexpressing a transduced PEG-3 gene in the sense orientation (S), displaying an aggressive progressed transformed phenotype, gain-of-function phenotype; E11-NMT/PEG-3 AS, a clone of E11-NMT cells stably expressing an antisense construct (AS) targeting the PEG-3 gene, displaying a non-progressed transformed phenotype, loss-of-function phenotype. Taken from Su et al. (29), Proc. Natl. Acad. Sci. USA, 1999.