The UK's biggest biotech firm, Celltech, has agreed to be taken over by the Belgian drugmaker UCB.
The agreed bid is for 550 pence a share, compared with Monday's closing price of 430.5p, and values Celltech at £1.5bn.
The deal will create Europe's second-largest bio-pharmaceutical firm, with Denmark's Novo Nordisk at number one.
Celltech employs about 1,900 people and had a turnover of more than £350m during its last financial year.
'Fair value'
UCB said it had also agreed to license the worldwide rights for Celltech's rheumatoid arthritis treatment CDP 870.
Celltech's chairman, Dr Peter Fellner, said the offer represented "fair value" for the company's shareholders.
Celltech reported pre-tax, pre-exceptional, profits of £52.2m for 2003, although after allowing for exceptional costs of £98.3m following acquisitions it had a pre-tax loss of £53.9m.
Roch Doliveux, chief executive of UCB Pharma, said the firm was looking forward to working with Celltech "to transform Celltech's and UCB's very promising pipeline into commercial value for our shareholders".
Samir Devani, an analyst at Code Securities, told the Reuters news agency that UCB's deal to license CDP 870 would put off any possible rival bids.
"There's no reason for anybody to come in [with a rival bid] if the rights to CDP 870 have already been signed over," he said.