Fig. 1.

Discovery of STM sialyltransferase by multiway differential display. (A) Total RNAs were isolated from normal human mammary epithelial cell strains (N, 76N, 70N; lanes 1 and 2), primary (P, 21NT, 21PT; lanes 3 and 4) and metastatic mammary tumor cell lines (M, 21MT-1, 21MT-2, MCF-7, and MDA-MB-435; lanes 5, 6, 7, and 8). The RNAs were reverse-transcribed with the T₁₂MA 3′-end anchored primer and amplified with T₁₂MA and OPA3 (AGTCAGCCAC), a 5′-end random primer. The position of the stm partial cDNA (125 bp), and another example of a differentially displayed cDNA, are indicated with arrows. (B) Northern blot analysis of differential stm gene expression. A cloned and ³²P-labeled partial stm cDNA obtained from differential display was used as a probe (upper). Ethidium bromide-staining of the gel used for the Northern blot (lower). Each lane contains 20 µg of total RNA. The 28S and 18S subunits of ribosomal RNA are shown.