The invention relates to induced pluripotent stem cells that are generated from cells, for example Adult Stem Cells, that are conditionally-immortalisable. In particular, the invention relates to induced pluripotent stem cells generated from stem cell lines comprising a controllable transgene for conditional immortalisation, and the progeny of those induced pluripotent stem cells. Induced pluripotent stem cells, progeny cells derived from those pluripotent cells, compositions comprising those cells, methods of making all of those cells, and uses of all of those cells are also described.