MSCs protect MOLM-13 cells by production of soluble factors, regulated by p53 activation. (A) Normal MSCs (N-MSC) were pretreated with 10μM Nutlin-3a (N3a) for 24 hours. MOLM-13 cells were treated with 800nM FI-700 for 24 hours in the presence or absence of normal MSCs. Cells were collected from upper compartment when culture inserts were used. NS indicates not significant. (B) MOLM-13 cells were treated with the indicated concentrations of FI-700 in MEM-α medium (control medium), MSC-conditioned medium (conditioned medium) or with normal MSCs. Asterisk (*) indicates significance at P < .05 (1-way ANOVA/Tukey).