Coexpression of antagonistic genes has been shown both for closely-related lineages (for example coexpression of antagonistic hematopoeisis-related genes, Miyamoto et al., 2002, Akashi et al., 2003, Ye et al., 2003, reviewed by Orkin, 2003, transient prespore expression of a prestalk-specific gene in Dictyostelium, Jermyn and Wiliams, 1995, coexpression of lineage-specific genes in pancreas development, Chiang and Melton, 2003, and coexpression of neurogenic genes, Briscoe et al., 2000, Rallu et al., 2002, Pierani et al., 2001, although the latter may be due to a transient effect of the misexpression method), and between more distantly-related lineages (for example expression of neural markers by hematopoietic precursors, Goolsby et al., 2003).
A semi-quantitative analysis of the expression of many hematopoietic genes was performed by Akashi et al. (2000), showing that lineage-specific (and antagonistic) genes were co-expressed at low levels in precursors, before respective upregulation and downregulation (see Rothenberg, 2000, Zhu and Emerson, 2002, for reviews). At an earlier stage of development, markers for different germ layers are also transiently co-expressed (Wardle and Smith, 2004).