Figure 1.

Differential display fragment A7-1 is preferentially expressed in JB6 P− cells. (A) Differential display with T₁₂MA and AP-7 primers was carried out on total RNA from P+ and P− cells and separated on a 6% denaturing polyacrylamide gel as described in Materials and Methods. Arrowheads indicate the position of a band, A7-1, reproducibly visible only in the P− lane. One set of duplicate samples is shown. (B) Northern analysis of total RNA (20 μg) prepared from untreated monolayer cultures of two independently derived P− cell lines (30–2a and SC21) and two independently derived P+ cell lines (Cl41 and Cl22) was carried out by using a ³²P-labeled A7-1 probe (upper panel). The arrow indicates the approximate size of the A7-1 band. The blot was stripped and reprobed with a ³²P-labeled 7S RNA probe to assess equivalent loading (lower panel).