Growth arrest and early death of <i>mTrop1</i>-null mice.

<p>(A) Whole litter from a representative HET crossing. Day 0: At birth all of the 10 pups were alive; KO mice were indistinguishable from their littermates. Days 2, 3: One pup (circled in red) is appreciably smaller than the others. Bottom: genomic PCR genotyping identified the small pup as KO (star). The KO <i>versus</i> WT and HET littermate difference in weight increased over days 2, 3 and 4 (KO pup weight: 1.35 g, 1.20 g, 1.20 g, respectively; litter mean weight (±SD): 1.82±0.14 g, 2.11±0.29 g, 2.44±0.19 g, respectively). (B, C) analysis of 5 different litters from independent HET breeding pairs (all with >6 generations of backcrossing to B6). (B) Kaplan-Meier survival curves of WT, HET and KO newborns. No differences were revealed between WT and HET; all KO pups died by day 4 (P<0.0001 <i>versus</i> WT or <i>versus</i> HET, log-rank test) (C) Growth curves of WT, HET and KO pups; no differences were revealed between WT and HET (P = 0.7321, two-way ANOVA); KO pups showed no weight increase from birth to day 4 (KO vs WT: P = 0.0003, two-way ANOVA). Stars indicate statistically significant differences at single time points (Bonferroni multiple comparisons): * P<0.05; *** P<0.001. Inset: a KO mouse at day 3 <i>versus</i> a HET littermate.