Disruption of CXCR4 abrogated signal transduction pathways and the proliferation of rat glioblastoma, RG2. (A) Representatives of combined individual clones with similar residual levels of CXCR4 from the rat glioblastoma cell line (RG2) with disrupted expression of CXCR4 by shRNA. Both western blotting and RT-PCR revealed decreased levels of CXCR4 in shrCXCR4-1 and shrCXCR4-3 clones, compared to the mock shGFP. (B) Disruption of CXCR4 impaired the phosphorylation of AKT and ERK without (AKT-p, ERK-p) or with induction of SDF1α (AKT-p/SDF-1, ERK-p/SDF-1α). (C) In vitro transwell assay indicated that inhibiting CXCR4 did not affect the invasiveness of RG2. (D) Methylcellulose colony formation assays indicated that the disruption of CXCR4 reduced the number of colonies. As shown was representative of similar results from two independent experiments.