s of investigation for future analysis into the dual roles of MYC in apoptosis and survival. It is hoped that such studies will prove fruitful and provide further insight into the complex role of this enigmatic protein. Methods Tissue Sample Preparation Transgenic mice expressing switchable pIns MYC ERTAM in pancreatic b cells or inv MYC ERTAM in SBK have been previously characterized and described. 8 12 week old male mice were treated with 4OHT or vehicle for 4, 8, 16 or 32 hours. Triplicate samples were collected for each time point for each of the four conditions, pIns MYC ERTAM 4OHT treated MYC ERTAM active, pIns MYC ERTAM vehi cle treated MYC inactive, Inv MYC ERTAM 4OHT treated MYC active, Inv MYC ERTAM vehicle treated MYC inactive.

All mice were housed and treated in accordance with protocols Carfilzomib and regulations sanctioned by the Home Office under the Animals Act of 1986. RNA Isolation and Microarray Hybridization A modified LCM protocol was devised to preserve RNA integrity. Fresh frozen pancreas sections were cut to a thickness of 15 um, bound to a MMI MembraneSlide and fixed in ice cold 100% ethanol for 2 mins. Sections were stained briefly with a 1% Toluidine Blue dye in 100%. Stained sections were dehydrated in 2 changes of 100% ethanol and 2 changes of xylene for 1 minute each, airdried for 2 minutes and finally left in a vacuum dessicator for 5 minutes before transportation to the laser capture platform. The SL uCut LCM system was used to isolate islets of Langerhans from surrounding exocrine tissue. RNA was collected using the RNA Microkit protocol.

The laser cap ture procedure was repeated on freshly cut pancreas sections to collect a total area of islet cells equal to roughly 1. 5 �� 106 um2 for each sample. Due to the thin ness of murine suprabasal epidermis, isolation of suffi cient good quality RNA for microarray hybridization from LCM of SBK proved difficult, a problem also noted by Agar et al. RNA was instead collected from 5 fresh frozen skin sections collected across several levels of the tissue. A modified version of the Affymetrix GeneChip 2 cycle target labelling in vitro transcription protocol was used, incorporating double volumes of polyA controls and reagents in the first round cRNA synthesis stage to increase the yield. 10 ug double amplified biotin labelled cRNA were hybridized to Affymetrix MOE430 2.

0 GeneChips as described in the Affymetrix GeneChip Expression Analysis Technical Manual. Data Analysis Data were normalized across all samples at the probe level using GC RMA. Analysis of gene expression data was performed using the Bioconductor microarray analysis packages in R and GeneSpring GX 7. 3. 1. 4OHT treated samples were normalized to their respective vehicle treated counter parts to ensure that normalized values corresponded to the fold change in gene expression due to activation of ERTAM. Removal of control and non responsive probes identified 12,349 probe sets. The custom R pack age Envisage was used to iden