BECN1 and neoplasm: Three subunits of the class III PI3K complex (Beclin 1, UVRAG and BIF-1) have been independently identified as tumour suppressors in mice and humans, and their mechanism of action in this context has been proposed to entail activation of autophagy, a catabolic pathway that is considered to mediate tumour suppression by scavenging damaged organelles that would otherwise cause DNA instability through the production of reactive oxygen species.