MFGE8 induces anti-PD-1-therapy resistance by promoting extracellular vesicle sorting of PD-L1

To elucidate which secreted factors in tumor tissues (TTs) are responsible for the upregulation of UBE4A as the tumor progresses, we inoculated tumors in mice and analyzed the 2- and 4-week TT fluid by mass spectrometry (MS). By combining molecular weight cut off(MWCO) and the identification of secreted proteins, we identified three candidate proteins.