In vitro- and in vivo-studies with ROCK1 inhibitors suggest that ROCK1 activation increases motility, invasiveness and metastasis through accelerated actin filament remodeling and/or through indirect effects on the stiffness of the extracellular matrix, for example in mouse models of breast cancer bone metastasis [21], in ovarian cancer cells [22], and in lung cancer cells [23]. Here, ROCK1 is linked to breast cancer.