Amino acid sequence of the cytoplasmic domain of β1 integrin in HBE or MCF-7 cells. (A) Agarose gel electrophoresis of RT-PCR products. Total RNA was extracted from HBE or MCF-7 cells which were quiescent and adherent to collagen IV, and cDNA encoding the cytoplasmic domain of β1 integrin was amplified by RT-PCR. The cDNA products were resolved in 1.6% (w/v) agarose gel electrophoresis with molecular size markers (Mr) and stained with etidium bromide. Molecular size of the cDNA products are indicated at right in bp. (B) The cDNA fragments of 462-bp were extracted from agarose gels and sequence analysis was carried out. Amino acid sequences of the three peptides with the highest affinity for α-actinin are underlined (adapted from ).