Hindlimbs of Pkdcc−/− (left) and control (right) neonates at birth. The mouse mutants for a putative protein kinase gene, Pkdcc (AW548124), have short limbs. The mineralized regions of the long bones of four limbs were specifically shortened, and cause of this abnormality is delayed formation of flat proliferative chondrocytes and hypertrophic chondrocytes. The background image is a parasagittal section of the humerus of a normal E15.5 embryo showing the differentiating chondrocytes. See Imuta et al., Developmental Dynamics 238:210–222, 2009. © 2009 Wiley-Liss, Inc.