BASEL, Switzerland – Top officials of Swiss pharmaceutical giant Roche Holding and Genentech Inc. are meeting Tuesday to discuss Roche's proposed $43.7 billion takeover bid for the U.S. biotechnology pioneer.

“But this is on an informal level,” Roche spokesman Daniel Piller said Tuesday. “It has no impact on this process.”

“The next step is really that the independent directors of Genentech have now to discuss and think what is their reaction position on our offer,” Piller told the Associated Press.

Roche Board Chairman Franz Humer said Monday he had advised Genentech Chief Executive Arthur Levinson a couple of hours before making the proposal public and that he would meet with him in San Francisco on Tuesday evening to discuss it.

Genentech, whose anticancer drug Avastin is widely prescribed, acknowledged the offer Monday and said it expected its independent directors would consider the bid, but gave no time frame.

Roche, which already owns 55.9 percent of the South San Francisco, Calif.-based drug maker, is offering $43.7 billion to take over the remaining shares. The offer is priced at $89 per share, 8.8 percent above Genentech's closing price Friday and 19 percent above where its stock traded last month. But Genentech's shares jumped $12.06, or nearly 15 percent, to close Monday at $93.88, indicating investors expected Roche would have to sweeten its offer.

“It is a bit to early to say,” Humer replied when asked which of the key researchers and managers would stay on following a Roche takeover. He said there were “certain legal impediments” to what can be discussed at this stage with Genentech management.

“Certainly though we are are developing plans so that we can keep the management on board and the scientists on board,” Humer said.

In morning trading, Genentech shares slipped 28 cents to $93.60 in the U.S.