A lymphoid-cell line, lacking the t(15;17) but having the PML and RARA genes in close proximity in specific phases of the cell cycle, was irradiated with 10 Gy of (60)Co, and the incidence of PML-RARA transcripts was analyzed by a highly sensitive PCR assay.     ///    "The data thus indicate that the PML and RARA genes are not particularly susceptible to the clastogenic effects of gamma-irradiation, and that, similar to what has been reported for other chromosomal translocations, transcriptionally active PML-RARA rearrangements can be generated in normal hematopoietic cells of different lineages without apparent oncogenic consequences.. "    ///    "Despite gene proximity, typical PML-RARA transcripts were only rarely detected in irradiated cells. "    ///    "PML-RARA transcripts were observed at low frequencies in isolated lymphoid and granulocytic cell populations, with similar incidence in both cell types. "