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 FcεRIα. Although we cannot exclude the possibility of nonspecific binding of anti-FcεRIα antibody (clone MAR-1), we provide evidence that macrophages in squamous cell carcinomas express FcεRIα and that IL-33 induces FcεRIα expression in bone marrow cell-derived macrophages.