Figure 1: Co-culture effect on cellular response to doxorubicin. Wild type human neuroblastoma (SK-N-SH WT) cells co-cultured with SK-N-SH WT cells (WT/WT) were compared to co-cultures of SK-N-SH WT cells with doxorubicin resistant cells (SK-N-SH DoxR) (WT/DoxR). Co-cultures were treated with and without doxorubicin at 10−7 or 10−6 M for 48 hours. Surviving cells were quantified using trypan blue staining. The cell survival ratio represents the number of live WT cells in the drug-treated co-culture divided by the number live cells in the untreated (control), * .