PPP1R1B and neoplasm: Briefly, 1 × 106 luciferase-labelled human DMS-53 SCLC cells stably overexpressing exogenous DARPP-32 or t-DARPP were injected into the left thorax of anesthetised SCID mice, and we observed increased tumour growth in mice harbouring DMS-53 cells overexpressing DARPP-32 or t-DARPP relative to mice that received control DMS-53 cells overexpressing LacZ (Fig. 3b).