1.   Another Advanced Cell researcher, Dr. Teruhiko Wakayama, who had cloned mice at the University of Hawaii, tried thousands of times before it worked.

2.   All three involved animal experiments, including an effort to clone a cow and another to clone a mouse.

3.   Cloning mice is more efficient, Yanagimachi said.

4.   He noted that while mice have been cloned, no one has cloned a rat.

5.   In the research announced Friday, scientists cloned mice and then compared the expression of six genes to normal mice.

6.   Scientists have already cloned mice, cows, goats, pigs, sheep and a wild ox, but the success rate is low.

7.   This reprogramming of DNA is presumably what happened when mice were cloned this July from adult cells.