During one of the most memorable conference sessions I attended, a researcher from Japan wowed an entire Keystone meeting on stem cells by announcing he had found a way to reprogram adult stem cells into embryonic stem cells using only a few factors. What those factors were, however, Shinya Yamanaka from Kyoto University wouldn?t say -- even after numerous probing questions from the audience.

Now, Yamanaka is revealing his secrets in the latest issue of Cell. He and his colleague describe translating adult fibroblasts into pluripotent stem cells using only four factors -- Oct 3/ 4, Sox2, c-Myc, and Klf4. Surprisingly, the researchers didn?t need to use Nanog, a key ingredient in maintaining pluripotency.

I hope my fellow conference attendees feel the findings are worth the wait. Personally, I?m skeptical of the claim that reprogramming -- a long sought-after mechanism that would sidestep ethical issues surrounding embryonic cells -- requires such simple steps. Only further experiments will reveal whether four factors are all you need to dive into reprogramming with full gusto.