MASTL inhibits cell spreading and attachment (related to Figure 1 ). (A) Western blot analysis of MASTL and GAPDH after MASTL silencing (48 h) with siRNAs #6 and #7 in MDA-MB-231 cells. (B–D) Quantification of cell attachment (normalized cell index, impedance) at the 2-h time point measured with xCELLigence after plating of single MDA-MB-231 cells (siControl or siMASTL, 48 h) on fibronectin silenced with siMASTL#6 (n = 4 biologically independent experiments, mean ± SD, unpaired t test; B), fibronectin silenced with siMASTL#7 (n = 2 biologically independent experiments; C), or collagen silenced with siMASTL#7 (n = 2 biologically independent experiments; D). (E) Western blot analysis of MASTL and tubulin in MDA-MB-231 cells after 24-h overexpression of EGFP-control or EGFP-MASTL WT. (F) Quantification of cell attachment at the 2-h time point (from Fig. 1 I curves) of siControl (48 h), siMASTL (48 h), or EGFP-MASTL WT–reexpressing (24 h silencing + 24 h expression of siRNA-resistant MASTL) MDA-MB-231 cells on collagen. See also Table S1.