MCPH1 and microcephaly: Brain sections from newborn mice showed that brain thickness in Mcph1−/−,Trp53−/− mice is reduced to the same extent as in Mcph1−/−,Trp53+/+ compared to Mcph1+/+,Trp53+/+ mice, ruling out that p53 inactivation is able to rescue the microcephaly (Fig. 7A).