VEGFB and isolated hemihyperplasia: To determine whether atenolol inhibits hemangioma endothelial differentiation independently of its beta blocker effects, we assessed VEGF-B–induced HemSC to endothelial differentiation using HemSCs isolated from 2 IH specimens (specimens 165, 167) in the presence of atenolol, its R(+) enantiomer, and R(+) propranolol as a positive control.