SMAD1 and cancer: Considering frequent RAS gene mutation in cancer, e.g. colon (∼40%) and non-small cell lung cancers (∼30%) [59], further experiments are to be performed to clarify which cell types Bmp2-Smad1 signal is critical in oncogene-induced senescence, and whether Bmp2-Smad1 signal and its target genes are disrupted in cancer with association to oncogene mutation.