Sensitivity of N2A stable clones to GCV.

(A–L) N2A, N2A-pGFAP-HSVtk, and N2A-pCMV-HSVtk cells were treated separately with 0, 1, 5, or 10 μg/ml of GCV for 5 days, and their live-cell phase images or fluorescent images were captured. (M) An MTT assay was performed to detect their cell viability under GCV challenge (n = 3). The morphology of N2A parent cells (A–D) and N2A-pGFAP-HSVtk cells (E–H) remained intact and their cell viability was maintained above 90%. (I–L) The number of N2A-pCMV-HSVtk cells was decreased in a dose-dependent manner. In addition, green fluorescent cells were still detectable among the surviving cells even after treatment with 10 μg/ml of GCV. (M) The results of the MTT assay for these three groups were consistent with the imaging results. Scale bar, 200 μm.