ESR1 and rhabdomyosarcoma: To exclude the possibility that inhibition by this drug may depend upon the inhibition of ER-α signaling, human rhabdomyosarcoma cell lines RH30, RD, and RH28 with constitutive STAT3 signaling that do not express ER-α were used in our study and most of the primary rhabdomyosarcoma tumors lack the expression of ER-α [54, 55].