SRF and cancer: The first study reporting that depletion of Mkl1/2 proteins reduced motility, invasion and colonization of metastatic tumor cells in an experimental in vivo metastasis assay [64] was further supported by the discovery of the Mkl1-binding protein, suppressor of cancer cell invasion (SCAI), which inhibited SRF/Mkl1-mediated expression of β1 integrin [68].