Negative correlations were detected, as shown in Fig. S7, between hub genes and tumour purity (CDH19, r = − 0.26, p = 4.29e−07; PLP1, r = − 0.311, p = 9.63E−10; RELN, r = − 0.382, p = 3.06e−14; TRIB3, r = − 0.138, p = 8.14e−03). This evidence concerns the gene PLP1 and neoplasm.