STAT3 and neoplasm: Other studies report that TA-MSCs secrete various cytokines, such as platelet-activating factor (PAF), asporin (ASPN), and IL-6, which enhance proliferation, migration and invasion properties of tumor cells via activation of multiple critical downstream pathways, including signal transducer and activator of transcription 3 (STAT3), protein kinase B (PKB/AKT), janus kinase 2 (JAK2) and ERK1/2 [29, 42, 43].