Casein kinase 1 epsilon inhibition decreases the cell adhesion of MCF7 breast epithelial cells. (a) to (d) MCF7 cells grown in hanging drop culture tend to form compact cell clusters under control conditions (dimethylsulfoxide (DMSO)). With increasing amounts of the casein kinase 1 epsilon (CK1ε) inhibitors - (a), (b) D4476, and (c), (d) IC261 - the large single-cluster formation is disrupted, and cells form smaller and disintegrated aggregates. After resuspending these aggregates by pipetting up and down seven times, a significantly higher number of single cells was observed to be released from clusters in conditions treated with (b) D4476 and (d) IC261, as normalized to control. ***P < 0.001, Student's t test, n = 3. (e), (f) MCF7 cells were seeded in the presence or absence of 5 μM IC261. Cell morphology was analyzed after 20 hours in (e) phase contrast or (f)after staining of actin filaments (phalloidin, green) and cell nuclei (Hoechst, blue). (g), (h) Dynamics of MCF7 cell adhesion was monitored for 20 hours using the xCELLigence System (Roche Applied Science). Cell adhesion is expressed as the cell index for two control wells (DMSO) and two experimental wells (2.5 μM IC261). (h) Treatment with IC261 did not affect the cell number (compared with control) during 20 hours of stimulation.