The invention relates to methods of altering gene expression by homologous recombination in a multipotent adult progenitor cell (MAPC). In particular, methods of producing a recombinant MAPC, of correcting a genetic defect in a mammal, of providing a functional and/or therapeutic protein to a mammal, and of transforming a MAPC are provided. MAPCs containing an erogenous DNA as well as recombinant MAPCs and their differentiated progeny are also provided.