Real-Time RT-PCR validation of microarray data. Real-Time RT-PCR analysis performed on cultured GBM cells generating tumor xenografts with nodular-like growth pattern, NL-type (PT1-3) or highly diffuse and invasive growth pattern, HD-type (PT4-6) to validate the microarray data. This was accomplished on randomly selected genes from Table 2 and showed, in arbitrary units. Expression levels are relative to the expression of the housekeeping peptidyl-prolyl cis-trans isomerase A (PPIA) gene transcript. Standard deviations are indicated as vertical bars. Gene name symbols used are those approved by the Human Genome Organization Gene Nomenclature Committee (http://www.genenames.org/).