To investigate the sensitivity of human NB cell lines to CHK1 inhibition, we examined the effects of the CHK1i PF-00477736 on the proliferation of four MYCN-amplified NB cell lines: NB-39-nu, SMS-SAN, CHP134, and SK-N-BE [19,20,21,22]. The gene discussed is PSMA1; the disease is neuroblastoma.