BT20 and MCF7 spheroids have a lower expression of death receptors.

(A) Confocal micrographs of BT20 and MCF7 cells cultured as 3D spheroids and 2D monolayer stained with antibodies against DR4 (red), DR5 (red) and EpCAM (green). (Scale bar  = 20 µm) (B) Flow cytometry histograms comparing DR4 and DR5 expression in BT20 and MCF7 spheroids and monolayer. (C) Western blot analysis of total DR4 and DR5 expression in cell lysates from BT20 and MCF7 spheroids and monolayer.