Related to Fig. 3 . Shorter CSPP1 constructs are less potent in stabilizing MTs in cells. (A–M) Kymographs of MT growth with 20 nM mCherry-EB3 together with the indicated GFP-CSPP1 constructs at the indicated concentrations. Scale bars, 2 μm (horizontal) and 60 s (vertical). Images of SDS-PAGE gels with purified proteins are included for each construct. Asterisk indicates full-length protein band. (N and O) Widefield fluorescence images of COS-7 cells overexpressing GFP-CSPP-L and stained for α-tubulin and acetylated tubulin (N) or EB1 (O). Scale bar, 20 μm. (P and Q) Quantification of mean acetylated tubulin intensity (P) or quantification of number of EB1 comets per 100 µm² (Q) per COS-7 cell (from images as in N and O). Quantification and statistics as in S1I. Total number of cells analyzed acetylated tubulin, EB1: control cells, n = 137, n = 111; cells overexpressing GFP-CSPP-L, n = 77, n = 75; cells overexpressing GFP-MTB+LZ+PD, n = 83, n = 72; cells overexpressing GFP-MTB+LZ, n = 70, n = 61; cells overexpressing GFP-H4+LZ, n = 50, n = 75. Bars represent pooled data from two independent experiments. Data for control and GFP-CSPP-L is the same as in Fig. S1 I. Error bars represent SEM. ***, P < 0.001; Kruskal–Wallis test followed by Dunn’s post-test. Source data are available for this figure: SourceData FS2.