RTKN2 and breast cancer: Importantly, cluster 1 was also marked by RTKN2, which was recently identified in healthy donor blood-derived Treg82, and the tumor-infiltrating Treg markers LAYN, MAGEH1, and CCR8, which associates with increased proliferative potential and suppressive capacity but most importantly poor prognosis in breast cancer, NSCLC, and CRC patients30,83.