Relative levels based on visual comparison of western blots. ++: expression equal to or greater than PMLRARα expression in the highest expressing line of MRP8-PMLRARα transgenic mice (line 556). +: expression present but less than PMLRARα expression in line 556. +/−: minimal expression. −: no signal on western blot.

When nonleukemic founder 4048 was euthanized at 37 days of age, its bone marrow was transplanted into lethally irradiated nontransgenic FVB/N mice. These mice were designated as 4048.1-4048.6. Mouse 4048.1 was euthanized for assessment of transgene expression and the other 5 recipient mice were monitored for illness.

Founders 4042, 4048, 4099, 4105, and 4114 exhibited abnormal skin growth similar to that seen in our MRP8-PMLRARα transgenic mice (data not shown).

Radiation can induce sarcomas in FVB/N recipients of transgenic marrow.

This founder was euthanized at 18 months of age for examination and assessment of transgene expression.