TMEM97 and neuroblastoma: A high affinity sigma-2 receptor ligand, PB221 (4-cyclohexyl-1-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl-propyl)] piperidine), derived from a class of N-cyclohexylpiperazine derivatives, has been recognized as a potent inhibitor of the proliferation of the SK-N-SH human neuroblastoma cell line in vitro [19].