(a) External levels of polySia on a panel of cancer cell lines with or without endoN treatment measured by flow cytometry using ch735 and fluorescent anti-human secondary. Data are the geometric mean fluorescence intensity (MFI), with the values reported as the average of three replicates and the error represented as the standard deviation of the mean. (b) Confocal microscopic images of endoN-treated and non-treated polySia expressing cancer cell lines to assess ch735 binding on the cell surface. Cells were stained with ch735 (green), wheat germ agglutinin (WGA, red) to stain the cell membrane, and Hoescht (blue) to stain nuclei. Scale bars, 10 μm. (c) Formalin-fixed, paraffin-embedded (FFPE) human tissue sections of SCLC and (d) adjacent normal tissue stained for polySia with mo735. Scale bars, 200 μm.