A method of generating an induced progenitor population (iPP) of cells and/or induced population of cells from somatic cells, comprising the steps:a) obtaining a starting cell population, wherein cells of the starting cell population comprise, or are contacted with, a nucleic acid molecule encoding four reprogramming factors under the control of a control element, wherein the four reprogramming factors are optionally Oct4, Klf4, Sox2 and c-Myc, and wherein the control element prevents or stops expression of the reprogramming factors under its control in the absence of induction by an inducing agent andb) transiently inducing expression of the reprogramming factors in the starting cell population to obtain an iPP,c) optionally isolating the iPP, andd) terminating the transient induction while the proliferative capacity of the iPP remains under the control of the one or more exogenous reprogramming factors to produce an induced population of cells.
