GPR61 and gastric cancer: Although only MAP3K9 has been specifically related with lung cancer, acting as a cell proliferation promoting factor (oncogene) [41], previous research has reported that an increased expression of RTKN1 was observed in multiple cancer types, including lung cancer [42, 43], whereas CABP5 and GPR61 were previously related with increased RNA expression in human gastric cancer tissue, and aberrant methylation patterns resulting from air pollution, respectively [44, 45].