Reduced basal cardiac function and elevated CaMKII in CKO mice. A, Crabp1 allele was interrupted by a 5 bp insertion containing a Not1 site and CKO genotype is confirmed by Not1 digestion. CRABP1 is absent in CKO mice generated in C57BL/6J background. UD: undigested, D: digested. B, Representative heart images of male normal WT and CKO mice (top). Ratios of heart-to-body weight (HW/BW) and -tibia length (HW/TL) of male WT and CKO mice at age 16-20 weeks (n=10 each). *P<0.05, **P<0.01 vs. WT (t-test). C, HW/TL ratio of female WT and CKO mice (n=5 each). *P<0.05 vs. WT (t-test). D, HW/TL ratio of male WT and CKO mice at the indicated age. *P<0.05, **P<0.01 (t-test; n=3 each for 2.5 months, n=10-11 for 5 months, and n=6 each for 8 months). E, Representative microphotographs of WGA staining (n=3 each). Scale bar: 20 μm. F, Summary of relative cell size in D. *P<0.05 (t-test). G, Representative M-mode echocardiographs (a, a’: end-systolic LVID, b, b’: end-diastolic LVID, c, c’: end-diastolic LVPW). H, Representative western blots of ventricular lysates from normal WT and CKO mice probed with antibodies against phospho-CaMKII at T287 and phospho-PLN at T 17 and S16.