Fig. 2. HOW(L) is the major HOW isoform at stages 6-10. Whole-mount wild-type embryo double labeled for Twist (A) and for HOW (B). The merged image (C) indicates that HOW is expressed in the nuclei of the Twist-positive mesodermal cells. (D) Western analysis of embryos at 0-1, 3-5 and 14-16 hours after egg laying with anti-HOW antibodies that recognize both the HOW(L) and HOW(S) isoforms. At early stages, only the HOW(L) isoform is detected. (E,F) In situ hybridization of wild-type embryos at stage 10 with how(L)-specific probe (E) or with how(S)-specific probe (F).