To the contrary, 3D culture systems derived from traditional 2D cell lines fail to properly recapitulate this feature of in vivo tumor tissue (e.g. tumor cell dormancy), where 3–6 weeks of culture growth is needed for these multicellular tumor spheroids to reach 400–600 μm in diameter and even at this size, proliferative (Ki67 positive) cells either extend throughout the spheroid [45–48] or are sparsely located on the periphery and the spheroid itself, shows signs of central necrosis [49]. The gene discussed is MKI67; the disease is neoplasm.