We show that DARPP-32 and t-DARPP promote SCLC proliferation, evasion from caspase-3-dependent apoptosis, activation of Akt and Erk, and increased tumour growth in mice receiving lung xenografts of human SCLC cells stably transduced to overexpress or ablate DARPP-32 isoforms. This evidence concerns the gene PPP1R1B and neoplasm.