Specifically, we observed strong DARPP-32 staining intensity (i.e. 3) in all six SCLC patient-derived specimens examined, and the percentage of DARPP-32 positive tumour cells was high (i.e. ≥80%) in four of six SCLC tissues and detectable (i.e. 10–30%) in the other two samples (Fig. 4g–l and Supplementary Table 2). This evidence concerns the gene PPP1R1B and small cell lung carcinoma.