TFRC and neoplasm: To explore the impact of Treg-specific CD71 haploinsufficiency on tumor growth, we exploited the Foxp3CreTfrc+/fl progeny: in their lymphoid organs, there was a trend for reduced frequency of CD71+ Tregs, which was compensated by CD71– Tregs (Supplemental Figure 2, A and B), leading to a comparable frequency of total Tregs (Supplemental Figure 2C), expressing significantly less CD71 (Supplemental Figure 2D).