A method for generating a culture that is purified or enriched in respect of cells of a selected lineage is described in which selectable marker, which is differentially expressed in cells of the selected lineage compared with its expression in other cells, is introduced into a multipotential cell and the multipotential cell is cultured to induce differentiation of the multipotential cell into a cell of the selected lineage, or into a mixture of cells including cells of the selected lineage, or is cultured to induce preferential survival of cells of the selected lineage. Those cells that express the selectable marker are then selected for. Progenitors of selected lineage are also described as is the use of the method in assay techniques.