Multiple sclerosis (MS) is the major inflammatory demyelinating disease of the central nervous system. There is strong evidence that an immune response in the brain is a critical component of the disease. In 1992, in a collaboration between academia and biotechnology, my colleagues and I showed that α4 integrin was the critical molecule involved in the homing of immune cells into the inflamed brain. Was it sheer luck that these results led to the development of a drug for MS?