Real‐time imaging of single steps for distal metastases formation in kdrl:eGFP Casper zebrafish embryo( These results suggest that individual CTCs are the main source of distal metastases in the zebrafish metastasis model, although they cannot form metastases as efficiently as CTC clusters (86% survived into a metastases) (Fig. 1f).Stable arrest of individual CTCs is associating with intra‐capillary morphology switch (ICMS)Intensive actin filaments assembly is associated with ICMS and arrest of CTCsMechanical stress stimulates RhoA activation and F‐actin filaments assembly in CTCsRhoA activation is necessary for the ICMS and arrest of CTCs in vivoTransient Fasudil treatment efficiently eliminates pulmonary metastasis in mouse melanoma and breast cancer model