THE bcl-2 proto-oncogene is activated by translocation in a variety of B-lymphoid tumours and synergizes with the c-myc oncogene in tumour progression¹. The mechanism of synergy is unclear but bcl-2 expression inhibits apoptosis^2–6, a property presumably pertinent to its proto-oncogenic mode of action⁴. We have shown that the c-myc gene is a potent inducer of apoptosis, in addition to its established role in mitogenesis⁷. Here we show that expression of the bcl-2 protein, Bcl-2, specifically abrogates c-mvoinduced apoptosis without affecting the c-myc mitogenic function. This provides a novel mechanism for oncogene cooperation, of potential importance both in carcinogenesis and in the evolution of drug resistance in tumours.