HTR1A and attention deficit-hyperactivity disorder: HTR1A also plays crucial roles in schizophrenia,[15, 16] wound healing,[17] and attention deficit hyperactivity disorder.[18] In addition, studies have shown that the HTR1A agonist sumatriptan inhibits insulin secretion[22] and increases the risk of type I diabetes by enhancing the activity of cytotoxic T cells.[23] However, research focusing on the role of HTR1A in tumors is limited.