Exclusive expression of Gab1 mRNA led by LSP sequence in 10W−1, especially in 10W−1L cells. One microgram of RNA from 10W+8, 10W−1E, and 10W−1L cells was subjected to reverse transcription reaction using oligo(dT)18 primer. For some samples, reverse transcriptase (RT) was not included in the reaction (lanes 1, 3, 5, 7, 9, and 11). cDNA, in turn, was provided for PCR with either −14F or LSP as 5′ primer and 2104R as 3′ primer. PCR products were analyzed by 1.2% agarose gel and visualized with ethidium bromide staining and UV exposure.