EVERYONE KNOWS THAT ROCHE WAS, AND ARGUABLY STILL is, the driver of Genentech's success. But not everyone knows that Roche owns a majority stake in the biotech behemoth, as it does in Japanese powerhouse Chugai. And that's by design. Roche's management has long held that the best way to derive good and lasting results from its smaller partners is to let them do what they do best and leave them alone while they do it. That philosophy has served them well, especially when revenues of some of their codeveloped and comarketed blockbuster products are considered. Just two, Genentech's Herceptin (trastuzumab) and Chugai's Epogin (epoetin beta), have earned billions.