BMC Genomics 2007, 8:139 http://www.biomedcentral.com/1471-2164/8/139 aPFcCitgi1uv2artenioe1nuronal differentiation involves p53 stabilization and PC12 neuronal differentiation involves p53 stabilization and activation. A) Immunoblot depicting total and phospho-serine 15 p53 protein levels over time following 50 ng/mL NGF 2.5S, with total actin protein levels serving as loading control. B) RT-PCR levels of p53 mRNA over time following NGF 2.5S treatment compared to β-actin loading control. C) Luci- ferase activity in PC12 cells transfected with p53TAluc reporter vector following NGF 2.5S treatment at indicated time intervals, where p ≤ 0.05. Error bars represent standard deviation. FAingaulyrseis2of p53 knockdown PC12 cell lines Analysis of p53 knockdown PC12 cell lines. A) RT-PCR and immu- noblot depicting levels of p53 mRNA and protein in wild-type naïve PC12 cells compared to 7-day NGF (50 ng/mL) differenti- ated wild-type and anti-p53 shRNA expressing PC12 cells. GAPDH mRNA levels serve as loading control for RT-PCR, while actin serves as immunoblot loading control. p53 and GAPDH mRNA levels in each sample were quantitated using ImageJ and normalized to naïve RNA levels, depicted under each band. PCR cycle number used is shown on right of gel image. p53 RNA and protein levels (and knockdown efficiency) were lowest in p53#3low cells, followed by p53#2mid and p53#4mid cell lines. B) Representative image of wild-type and p53#3low PC12 cells fol- lowing 3 days treatment with 50 ng/mL NGF. Page 3 of 17 (page number not for citation purposes)