Expression of cell cycle-related genes during postnatal cardiac development of SMA mice. Heterozygous littermates (Het) were used as controls. (A) Microarray analysis of genes differentially expressed in the heart of SMA mice (n = 5). Tissue samples were collected on P5. Gene Ontology analysis shows that cell cycle-related genes are primarily affected. (B) Heat map showing log2 fold changes of expression levels for a subset of cell cycle-related genes (SMA over Het), analysed by real-time RT-PCR. Cardiac RNA samples were obtained from P0, P2, P4, and P6 mice (n = 3), respectively; gene-expression levels were normalized to Gapdh. (C–F) Histograms showing six mitosis-related genes that are downregulated in the heart of SMA mice on P0, P2, P4, and/or P6 (n = 4). (G) Western blotting analysis of Survivin, AURKB and SMN levels in hearts of mice aged P0, P2, P4, and P6. Protein levels were normalized to β-Tubulin. (H–J) Quantitation of the protein data from (G) and unpublished data (n = 3). For (C–F) and (H–J), *P< 0.05, **P < 0.01, ***P < 0.001.