In the mid-1960s, Rodbell was studying enzymes. At that time, the only test medium available was crude chunks of fat tissue. To get more precise results, Rodbell developed a method for isolating single fat cells from the fat tissue. Because fat floats, Rodbell first put the minced tissue in a liquid and then treated the floating cells with a substance called collagenase to separate the fat cells from other cells.

"Great," he shouted, but are they viable cells?"

• –Bernardo Houssay

Rodbell's 1980 commentary on his 1964 paper, which became a "Citation Classic."