Fluorescent immunocytochemistry of CK19 protein in CRC cell lines. A: the early-staged cell line, LS 174T cells (200 ×). B: the late-staged cell line, LoVo cells (200 ×). Both the cells were stained for cellular CK19 (a and d) with mouse anti-human CK19 antibody. Secondary antibody, Cy3-conjugated goat anti-mouse antibody. b and e, nuclear stain (DAPI) of cells from a and d. c, merged image from a and b; f, merged image from d and e.