Consistent with these studies, we found p21 is a direct target of RBP2 regulation in NET tumor cell lines.8, 18, 19 However, unlike the previous studies in non-NET cells, we found no RBP2-dependent change in p27 expression in neuroendocrine cells, suggesting RBP2 may interact with different targets in a tissue or cell type-specific manner. Here, RBP2 is linked to neoplasm.