Response to Comment on "Tumor-initiating cells establish an IL-33-TGF-β niche signaling loop to promote cancer progression".

Kamphuis et al. argue that macrophages accumulated in the proximity of tumor-initiating cells do not express the high-affinity immunoglobulin E receptor FceRIα. Although we cannot exclude the possibility of nonspecific binding of anti-FceRIα antibody (clone MAR-1), we provide evidence that macrophages in squamous cell carcinomas express FceRIα and that IL-33 induces FceRIα expression in bone marrow cell–derived macrophages.