[Capacity of the polynucleotide phosphorylase-releasing factor to stimulate hybrid cell growth].

The capacity of the partially purified preparation of the polynucleotide phosphorylase releasing factor (PNP-ase RF) from Walker sarcoma for stimulating the growth of hybrid cells and parent myeloma cells has been studied. The preparation of PNP-ase RF at a concentration of 500-50 micrograms/ml has been shown to induce the 3- to 10-fold increase of the number of cells in the culture by the 5th day of incubation without changing the medium.