DRD1 and non-small cell lung carcinoma: In the present study, expression and methylation of dopamine receptor D1 (DRD1) were measured using RNA sequencing (RNAseq) and reverse transcription polymerase chain reaction (RT‐PCR) in non‐small cell lung cancer (NSCLC) samples, and validated using publicly available datasets, including The Cancer Genome Atlas (TCGA).