Fig. 3 Rfx2 functions upstream of early asymmetric LPM genes. In 19–21 somite-stage rfx2 morphants spaw was expressed in the lateral plate mesoderm on the left side (A, typical of wt embryos) as well as on the right side (B), bilaterally (C), or was not expressed (D). At the 22–24 somite-stage, the two lefty genes are expressed asymmetrically, with lft1 predominantly in the left diencephalon and lft2 expressed in the left heart field. Individual rfx2 morphants displayed this normal left-sided expression (E), or aberrant right-sided expression in both the diencephalon and heart field (F), bilateral expression in both (G), or an absence of expression (H). Midline expression of lft1 was normal in morphants. myod1 expression in somites was used to stage embryos. Embryos shown are rfx2 AUGMO; rfx2 SBMO are similar. Histograms depicting the percentages of spaw (I), lft1 (J) and lft2 (K) expression patterns in wild-type and rfx2 morphant embryos.