['Inhibition of cell-cycle progression is a target for the treatment of cancer. 3-Oxoolean-12-en-27-oic acid (3-OOLA) has shown significant anticancer activity towards diverse cancer cells, but has not been investigated for non-small cell lung carcinoma (NSCLC) cells. In this study, we investigated the antiproliferative effect of 3-OOLA in NSCLC cell lines and its underlying mechanism.', 'The MTT assay, bromodeoxyuridine (BrdU) incorporation assay, and flow cytometry were used for cell proliferation studies, and annexin V staining for apoptotic effects. Western blot analysis was used to evaluate expression of cell-cycle regulatory proteins, such as cyclins and cyclin-dependent kinases (CDKs).', '3-OOLA caused G0/G1 phase cell-cycle arrest without inducing apoptosis in NSCLC cells, and Western blot analyses demonstrated down-regulation of cyclin D1, cyclin E and phosphorylated Rb.'] Does 3-Oxoolean-12-en-27-oic acid inhibit the proliferation of non-small cell lung carcinoma cells by inducing cell-cycle arrest at G0/G1 phase?