SMAD3 and small cell lung carcinoma: On the other hand, the other group (lower triangle in Figure 2A,i; called as group B henceforth) contained REST, SMAD3, and ZEB1 are suggested markers/regulators of non-neuroendocrine (NE) or mesenchymal subtype(s) of SCLC (Borromeo et al., 2016; Tlemsani et al., 2020).