TGFB1 and neuroblastoma: In addition to inhibitory signals, the availability of soluble factors in the TME, including galactin 1 and 3, TGF-β, and IL-10, can trigger T cell inhibitory pathways or inhibit T cell function [67,69,70,71,72], while secretory HMGB1 may be responsible for Treg differentiation in the neuroblastoma TME [73].