Figure 4.

p53 activation induces scratch2 expression in the spinal cord. (a) Scratch2 does not regulate p53 transcription. Real-time RT-PCR from embryos injected with control (MOC), scratch2, p53 or scratch2 plus p53 MOs. The transcription of p53 is not affected by scratch2 knockdown, but its transcriptional activity, measured by the levels of its readout mdm2, is increased. (b) Flat-mounted spinal cords from 24 h.p.f. embryos showing the apoptosis induced by camptothecin (CPT)-mediated p53 activation.¹⁴ (c) Real-time RT-PCR to assess the transcription of p53, its targets puma and mdm2 and of scratch2 in embryos subjected to the treatments shown in b. scratch2 transcription is activated in response to CPT treatment. (d) scratch2 is activated in ectopic spinal cord cells on CPT treatment in a p53-dependent manner. Real-time RT-PCR data in a are means±S.E.M. of five independent experiments and c shows a representative experiment (n=3), with each point examined in triplicate in all cases. ^*P<0.05: ^**P<0.01