During the late 1970s, Axel, along with microbiologist Saul J. Silverstein and Geneticist Michael H. Wigler, discovered a technique of cotransformation via transfection, a process which allows foreign DNA to be inserted into a host cell to produce certain proteins. A family of patents, now colloquially referred to as the "Axel patents", covering this technique were filed for February 1980 and were issued in August 1983. As a fundamental process in recombinant DNA research as performed at pharmaceutical and biotech companies, this patent proved quite lucrative for Columbia University, earning it almost $100 million a year at one time, and a top spot on the list of top universities by licensing revenue. The Axel patents expired in August 2000.