Synergy of HBZ, Akt, and BCLxL in the proliferation of Ink4a/Arf‐null T cells in vitro. (a) Scheme for the induction of T cells and retroviral infection (left), and schematic drawings of the retrovirus vectors for HBZ, myristoylated Akt, and BCLxL (not to scale) that co‐express surrogate markers human (h)CD8, GFP, and hCD4, respectively (right). These markers allow the identification of genes transduced in a given cell. (b) Growth of Ink4a/Arf‐null T cells transduced with the indicated genes in the presence (left) or absence (middle) of cytokines (interleukin‐7 [IL7] and FMS‐like tyrosine kinase 3 [Flt3]‐ligand) in bulk culture on OP9‐DL1 stromal cells. Results using Ink4a/Arf‐proficient T cells in the absence of cytokines are also presented (right). (c) Expression of hCD8, GFP, and hCD4 before (left) and 7 days after (right) the initiation of culture in the absence of cytokines. (d) Expression of transduced genes in T cells. Ink4a/Arf‐null T cells were transduced with the indicated genes as in (a), and subjected to Western blot analysis for the expression of myc‐tagged HBZ, Akt, phospho‐Akt (Ser473), and BCLxL. Anti‐α‐tubulin blots were included as loading controls.