CCND1 and non-small cell lung carcinoma: To confirm whether the negative correlation was observed in other cancer types, we obtained proton RBE values (relative to 60Co gamma-ray) of 17 human NSCLC cell lines from a previously published study [8] and found a similar negative correlation between CCND1 mRNA and proton RBE (r = −0.55, p = 0.010; Figure S2B).