MAP2K7 and cancer: As the activation of MEK/ERK signaling pathway is another key pathway for cancer cell proliferation [10], we next checked whether TRAIL regulates this pathway; we found that the phosphorylation levels of MEK (P-MEK), and ERK (P-ERK) proteins were all decreased after MSC-sTRAIL treatment, compared with the MSC-EV group, in Nalm-6 cells (Figure 2C).