The second position of codon 273 in p53 of Panc-1 is mutated, possessing an "A" instead of a "G". (A) All p53 exon 8 polonies are shown following Sybr Green I staining. (B) The position was shown to harbor a G → A mutation by performing independent single base extensions with Cy-5 labeled: dATP (blue) and dGTP (red). Extensions with Cy-5 labeled dCTP and dUTP did not yield any significant signal (data not shown). Colors are artificial in both images.