Fig. 4

Comparison and Classification of Raman spectra of human GBM wildtype cell lines. (a) Average spectrum (solid line) and first standard deviation (shade) for the indicated cell lines. Raman shifts where the difference exceeded the double standard deviation are shaded in light grey. (b) Cropped western immunoblot with an anti-Cx43 antibody (bottom) and an anti-vinculin antibody (loading control, top). (1: blot ladder with molecular weight indicated to the left, 2: T98G, 3: U87MG, 4: Ln229, 5: Ln18. Exposure time: 3 min. 6: Lane 3 at lower exposure time (7.5 s)). Uncropped blots in Supplementary Material S6. (c) Epifluorescent and correlating brightfield images of a HEK293 cell expressing Cx43-mTagBFP2 (*, aprox. cell borders denoted by dotted line) and an adjacent wildtype cell (wt). Raman sampling for Cx43-mTagBFP2 was conducted along the blue line; for wildtype, along the red line. (d) Brightfield images of probed wildtype cells. White bar: \(\:\approx\:\)5 μm. (e) Effect sizes of the intensity differences at the indicated Raman shifts between HEK293 cells expressing Cx43-mTagBFP2 and the indicated cell lines. Ln18 (brown), Ln229 (dark ocher), T98G (light ocher), U87MG (turquoise). The horizontal lines represent the significance levels. Dots centered below the line do not reach the significance level. (f,g) ROC curves of the coarse and medium Gaussian SVMs using all Raman shifts and the most significant Raman shifts, i.e., those where the intensity difference exceeded the double standard deviation. TPR: true positive rate FPR: false positive rate.