Two genes whose functions in tumor escape remain elusive, OPRD1, encoding the delta (δ) opioid receptor, and SLC19A1, a folate transporter, were identified as upregulated in invasive melanoma cells and were selected for proof-of-principle perturbation to validate the predictions from the above single-cell transcriptomics and bioinformatics analyses. This evidence concerns the gene OPRD1 and neoplasm.