Three probes were used for the chromosomal assignment of the human SPI1 oncogene: cDb1 and RaB2 correspond respectively to murine Spi1 and human SPI1 cDNA probes; C45a6B probe is a murine genomic DNA sequence located in the Spi1 5' region and is known as a major SFFV integration site in murine erythroleukemia cells.