Figure 1.

Subunits of system ${\mathrm{x}}_{\mathrm{C}}^{-}$ are expressed in glioma cell lines and patient tumor samples. A, RT-PCR indicated that transcripts of catalytic subunit xCT and the regulatory subunit 4F2hc of system ${\mathrm{x}}_{\mathrm{C}}^{-}$ are expressed in primary cultures of rat astrocytes and all glioma cell lines tested; four lines are shown. B, protein expression of xCT and 4F2hc are shown in human astrocytes and five human glioma cell lines. This is compared with the glutamate transporter GLT-1, expressed robustly in mature astrocytes but less so in human fetal astrocytes (immature). C, protein expression of system ${\mathrm{x}}_{\mathrm{C}}^{-}$ subunits in five GBM patient tissues are shown from individuals aged 51 to 72 y. β-Actin is shown as a control for protein loading efficiency. The approximate molecular weights of the proteins are indicated to the right as each blot image was cropped for clarity.