GPR18 and lung cancer: As shown in Fig. 3g, we were able to cross-validate the prognosticity of GPR18 mRNA expression levels (median cutoffs) in the Caldas early breast cancer cohort40 (N = 113), as well as two independent lung cancer cohorts, namely the GSE37745 (N = 196)41 and CAARRAY (N = 468) using Kaplan–Meier plotter42.