EGFR and central nervous system cancer: To determine whether DC vaccination preferentially altered genes distinguishing GSCs from non-stem gliomas, Principal Component Analysis (PCA) was performed using vaccine-altered transcripts (Fig. 1A), Shh and Egfr pathway transcripts (Fig. 1A), or independent immune-modulating gene transcripts, from human GBM and mouse GL26 microarray profiles, and the first three principal components statistically generated and plotted using GeneSpring software (Fig. S2A).