"What it does: Makes and sells biochemical assays — mixtures of antibodies, proteins, and fluorescent molecules — that help scientists determine which elements turn certain genes on and off, enabling them to create new drugs. Why it's growing: Each year, Active Motif develops assays that target 12 to 15 genes with the greatest market demand, including those linked with cancer and diabetes. Customers: Pharmaceutical companies, biotech outfits, and universities. Serial entrepreneur: Founder and CEO Joe Fernandez, a biologist, co-founded another biotech company, Invitrogen, in 1987. The business went public in 1999 and now has a market capitalization of $4.4 billion."