RB1 and lung adenocarcinoma: On the contrary, miRNAs upregulated in ADCs included miR-215, which has been shown to modulate gastric tumor cell proliferation by targeting RB1 [28], and miR-375, which has been observed to be upregulated in lung adenocarcinoma but downregulated in lung squamous cell carcinoma, and promotes cell proliferation by decreasing levels of ITPKB, a putative tumor suppressor [29,30].