Significance Although a role for β-adrenergic receptor (ADRB) in cancer progression was suggested a long time ago, our serendipitous observation of the propranolol efficacy in treating infantile hemangioma (IH) has driven attention in exploring the antitumor properties of β-blockers. We identified Aquaporine-1 (AQP1) as a player in antitumor propranolol response and as a histological marker of IH vascular structures including telocytes, which are dendritic cells that form a distinctive peripheral layer in IH. We conclude that IH sensitivity to propranolol may rely, at least in part, on a cross talk between lesional vascular cells and stromal telocytes.