AKT1 and central nervous system cancer: To this end, 1) control- and SPARC-expressing U87 cells or LN443 cells treated with control or SPARC siRNAs were untreated or subjected to TMZ or radiation therapy (RT), and 2) control- and SPARC-expressing U87 cells, LN443 cells, and human primary glioma cell lines treated with control, HSP27, SPARC, or AKT siRNAs or AKT inhibitor IV were subjected to Western blot analyses to assess tumor cell survival and death signaling, and were subjected to clonogenic assays to determine whether the treatments affect tumor cell survival and/or sensitize tumor cells to TMZ treatment.