CDK1 and malignant colon neoplasm: Furthermore, pseudoguaianolide (a 5/7 bicyclic compound) SLs of 6-O-angeloylplenolin, coronopilin, pulchelloid A and hymenoratin caused G2/M-phase arrest by activating cyclin B1-Cdk1/p-Cdk1 in multiple myeloma, leukemia and colon cancer cells, respectively [69,70,71,72,73].