ADRB2 and retinopathy of prematurity: Indeed, after birth, β2-ARs appear to play a predominant role in coupling hypoxia to excessive vascular growth in the proliferative phase of ROP as it occurs in infantile hemangioma in which β2-AR blockade with propranolol, a non-selective β-AR antagonist, is the treatment of choice to prevent chaotic vessel proliferation.