"For the past four years, life-science companies have been the significant driver here," Jim Mazzarelli, Liberty SVP and regional director, tells GlobeSt.com. He estimates such firms now account for between 60% and 70% of the western suburb's economic growth, and, "we have an unprecedented number of tenants looking to expand."

Rental rates in the park for this type of tenant range from $15 per sf for lab space to $6 per sf for light manufacturing space, all triple-net, according to Mazzarelli. Rates for space in one-story and mid-rise office buildings range from $20 per sf to $27 per sf, excluding electric. He declined to disclose the aggregate value of individual tenant's leases.

The largest is by Fujirebio Diagnostics, formerly Centocor Diagnostics, which was acquired by Tokyo-based Fujirebio Inc. It is adding 18,000 sf to take its total to 75,567 sf of industrial space in the 187,916-sf building at 250 Great Valley Pkwy. At the same time it renews for 17,292 sf at 508 Lapp Rd.

Locally based LifeSensors Inc. more than doubles its space, renewing and extending a lease at 271 Great Valley Pkwy. from 4,800 sf to 9,125 sf. Frontage Laboratories, also based here, more than triples its commitment, expanding from 5,300 sf of flex space at 111 Great Valley Pkwy. to 16,558 sf.

UK-based Ciphergen Biosystems moves from 117 to 277 Great Valley Pkwy. and expands from 3,406 sf to 4,500 sf. Locally based Interprod Inc. LLC adds 2,700 sf of flex space to take its total space at 291 Great Valley Pkwy. to 7,200 sf. These leases along with a 3,406-sf expansion by Brandywine Children's House to a total of 12,445 sf at 123 Great Valley Pkwy., and a more than doubling of Lyons Media at 20 Valley Stream Pkwy. to 2,721 sf, take overall occupancy in Liberty's share of the park to 93%. The Great Valley center is Liberty's largest suburban asset. The park anchors the Route 202 corridor, and will gain an extension to the Pennsylvania Turnpike in 2008.