PTPRZ1 and small cell lung carcinoma: While the introduction of the first construct shZ1#1 in SCLC cells did not appear to down-regulate PTPRZ1 mRNA levels as compared to control shLUC when measured by quantitative RT-PCR, significant reduction in mRNA expression of 75% using shZ1#2 and 60% using shZ1#3 could be observed in the expression of PTPRZ1 in the SCLC cell lines H69 and H1930 (Figure 3A).