Roche said Tuesday it will pay $3.4 billion to purchase US-based drug testing instrument maker Ventana Medical Systems.

Ventana will keep its headquarters in Tucson, AZ, while its CEO Christopher Gleeson will join the board of Roche’s diagnostics division, the companies said in a statement.

Wall Street analysts said the offer from Roche came as no surprise as the Swiss drugmaker has been trying to take over Ventana since June, and extended offers five times before clinching the deal.

Ventana currently employs 800 people and in 2006 had $238.2 million in sales of chemicals and instrument used to automatically prepare tissue samples for cancer screening and the testing of new drugs.