Human differentiation-stimulating factor (leukemia inhibitory factor, human interleukin DA) gene maps distal to the Ewing sarcoma breakpoint on 22q.

The human gene encoding differentiation-stimulating factor (D-factor) has previously been isolated and shown to be identical to leukemia inhibitory factor (LIF). We have determined a fine structure map of approximately 20-kb surrounding the D-factor/LIF gene. Southern blot analysis using a somatic cell hybrid panel shows that the gene maps to chromosome 22. D-factor/LIF was further sublocalized to 22q11.2----q13.1, distal to a Ewing sarcoma (ES) breakpoint, using a second somatic cell hybrid panel. Probes to the 5' and 3' regions of the locus and the cDNA were used to screen for restriction fragment length polymorphisms, but none were detected. Analysis by pulsed field gel electrophoresis suggests that D-factor/LIF is not near the ES breakpoint.