MAPK3 and breast carcinoma: As shown in Figs. 6b and S7a, the expression level of phosphorylated ERK1/2 (p-ERK1/2) in breast cancer cells was remarkably increased in the DR-Exos-treated group compared with that of the control and DS-Exos-treated group, whereas the phosphorylation of Akt and STAT3 was not changed.