TABLE 1.
E2f-2 loss extends the viability of Rb null micea
| Mouse genetic background and age | No. of mice
|
Total | ||
|---|---|---|---|---|
| Rb+/+ | Rb+/− | Rb−/− | ||
| E2f2+/− | ||||
| E12.5 | 6 | 15 | 4 | 25 |
| E13.5 | 10 | 18 | 7 | 35 |
| E15.5 | 7 | 13 | 0 | 20 |
| E16.5 | 2 | 7 | 0 | 9 |
| E2f2−/− | ||||
| E12.5 | 12 | 36 | 16 | 64 |
| E13.5 | 23 | 39 | 16 | 78 |
| E15.5 | 11 | 30 | 7 | 48 |
| E16.5 | 10 | 17 | 2 | 29 |
a
Mice were determined to be alive on the basis of the presence of a heartbeat. The numbers of live Rb null embryos recovered at different gestational ages were assessed as a function of the E2f-2 status of the mice. Rb null mice lacking E2f-2 were collected at E16.5, whereas Rb null mice on an E2f2+/− background were not collected alive after E13.5.