A selective medium (GAMA) for the isolation of somatic cell hybrids from HPRT- and APRT- mutant cells.

A medium is described which can be used for the selection of somatic cell hybrids between HPRT- and APRT- mutant cells. This medium, called GAMA, contains as its relevant constituents the following: the purines guanine and adenine and the purine biosynthetic pathway inhibitors mycophenolic adic, which blocks conversion of adenine ribonucleotides to guanine ribonucleotides, and azaserine, which blocks de novo purine synthesis.