The present invention relates to a method for storing cells, wherein the cells are stored in a composition comprising a base nutritive medium and liposomes at temperatures in the range of -196 DEG C to 37 DEG C, characterized in that the liposomes comprise one or more sterols and that the cells are tumor cells. More specifically, the invention relates to simple and effective methods for storing tumor cells, wherein the RNA and/or DNA in the cells is essentially not degraded, such that the RNA and/or DNA can be analzed after storage.