SP1 and small cell lung carcinoma: In addition to high levels of E2F1 (95.96%) and MMP-9 (86.67%) in SCLC, IHC staining in 90 SCLC samples revealed positive Sp1 and p65 expression in 93.33% (84/90) and 98.89% (89/90) of the cases, respectively (Figure 7A).