Next, we aimed to further validate the role of STAT3 in selectively packaging miR-378a-3p and miR-378d into exosomes and found that miR-378 expression was positively correlated with STAT3 expression in breast cancer based on the TCGA database (n = 470) (p < 0.001) (Fig. 6f). Here, STAT3 is linked to breast carcinoma.