B shCtr and shM2 H1299 cells were treated by 5-FU (50 μM; 24 h). Then drugs were washed out and the cells were cultured in normal DMEM medium (Ctr) or conditioned medium from non-treated cells or co-cultured with non-treated cells in transwells (separated by the filter) for another 24 h. The cell viability of 5-FU treated cells was determined using MTT assay. Data information: data were analyzed using two-way ANOVA with Bonferroni post-test and shown as mean ± SEM; * P < 0.05, ** P < 0.01, *** P < 0.001, ns, not significant. 