YM155 arrests cell cycle at G1/S or G2/M. H1299 non-small cell lung cancer cells were treated with volasertib (BI6727, 40 nM) to arrest cell cycle at G2/M before releasing into the media containing DMSO, BI6727 (40 nM), YM155 (40 nM) or YM/BI (40 nM each). Flow cytometry was performed at 4, 8, 24 hours later to determine the nuclear DNA contents (A). H1299 cells were synchronized with mimosine at G1/S. They were then released into media containing either DMSO (left panel) or YM155 (40 nM, right) on top. DNA content (DNA con) or BrdU incorporation (BrdU Inc) were monitored overtime at 4, 8, 24 hour. The percentages represented in the BrdU boxes are cells at S phase (upper) and G1 (lower) respectively (B). H1299 cells are arrested in M phase by nocodazole (50ng/ml) before released into medium containing DMSO (left column) or YM155 (40 nM, right) 4, 8, 12, 16, 20 and 24 hours. Passage through M and S were followed by flow cytometry (C). Cells were arrested in G1/S by mimosine (200 μM). Cells are released then into media with DMSO (left) or YM155 (40 nM, right). Cell cycle protein levels were followed with Western Blot at 0, 4, 8, 12, 16, 24 hours. Beta actin (ACTB) was used as loading control (D).