LIMK1 and breast cancer: To more precisely determine cell-based LIMK inhibitor activity, MCF7 breast cancer cells were treated with 2 μg/mL doxorubicin, which strongly increases cofilin phosphorylation through increased p53-mediated transcription of LIMK2 and RhoC genes [12] to increase the dynamic range and signal-to-noise ratio of the assay, and varying concentrations of LIMK inhibitors for 18 hr, then cells were fixed and stained for immunofluorescence determination of phosphorylated cofilin intensity.