CD4 and astrocytoma (excluding glioblastoma): It was shown that microinjection of few HIV-infected human astrocytoma cells (U87-CD4-CCR5) led to significant neuronal apoptosis in connexin 43 expressing mice, whereas hGFAP-cre Cx43fl/fl mice (connexin 43 negative) were relatively resistant to the toxic effects of U87-CD4-CCR5 cells.