The sales force, Pfizer's single biggest expense, is in many ways the core of its business.

This successful operation lies at the core of Goodrich's business.

The core of our business is in adventure training and personal development.

He said the two divisions, which are the core of the company's business, were "showing improvement on a daily basis."

"The core of my business are my friends," he says.

A good environment is at the core of our business.

The competition threatens the core of Nintendo's business, which is software.

"We want to concentrate on the core of our business, the top end of the market."

Long-distance calling, the core of the company's business, rose by 8 percent.

"The core of our business was office buildings, but over the last three to four years we have shifted to urban retail," he said.