Abstract: The present invention provides for a method of isolating and/or propagating porcine stem cells, more specifically pluripotential porcine embryonic stem cells. The pluripotential cells are isolated and/or propagated by the use of a selectable marker gene which is inserted into the genetic material of the cells, and which permits the survival and growth of the porcine embryonic stem cells. The selectable marker gene is inserted so as to be regulated by a control or promoter polynucleotide sequence in the embryonic stem cells, for example the promoter polynucleotide sequence being the porcine Oct-4 promoter sequence of the present invention. The invention also provides for a transgenic pig which will constitute a source of the pluripotent cells.