TNFRSF10B and neoplasm: Confocal micrographs indicated a strong staining for surface death receptor expression in BT20 (DR4 and DR5) and MCF7 cells (DR4 only) cultured as a monolayer and a weak or no staining in BT20 (weak for DR4 and no staining for DR5) and MCF7 (no staining for either DR4 or DR5) cells cultured as 3D tumor spheroids (Fig. 1A).