Median fold change (PDAC/Normal) of selected genes chosen for validation by Q-RT PCR.

Microarray results were validated by quantitative real time PCR (Q-RT PCR) using SYBR green based chemistry. 3 genes shown to be up-regulated by microarray (ANKRD22, ANXA3, ARG1) and 3 down-regulated (FCER1A, GRAMD1C, and MS4A1) genes were validated in a randomly selected subset of samples that included 9 healthy controls and 12 PC patients. The fold-change in gene expression was determined by the 2-ΔΔCt method using the same human reference RNA as the standard employed in the microarray. Correlation between microarray and Q-RT PCR results were determined through calculation of the median fold change for the PDAC and healthy samples by Q-RT PCR and comparing it to the fold change seen by microarray to determine whether the gene was differentially expressed in the same direction using both methods.