Tandem affinity purification of Keratin 23. Confocal immunofluorescence images of SW480 cells overexpressing KRT23. A) Smad4 re-expressing SW480 cells B) Smad4 negative SW480 cells. KRT23 was visualized by α-Flag M2 antibody. C) FLAG eluates from the tandem affinity purification experiments with TAP-KRT23 were separated on a standard 1D-PAGE and proteins visualized by silver staining. The protein names corresponding to each numbered band given in table 2.