On the cover: Bmpr1a deletion assessed by whole-mount LacZ staining: Patchy LacZ staining shown in pulmonary lobar vessels (left) and aorta (upper right) of adult SM22α;TRE-Cre;R26R;Bmpr1a^flox/flox mutant mouse. This patchy staining was also seen in cardiovascular tissues of E11.5 mutant embryo as seen in the right atrium and ventricle of the heart (lower right). See related article, page 380.