FIG. 1.

Identification of the B-KSR1 isoform. (A) A Northern blot containing RNA isolated from various mouse tissues was hybridized with a probe corresponding to the amino-terminal region of murine KSR1. Size markers are indicated in kilobases. (B) As for panel A except that the blot was hybridized with a probe corresponding to a 1-kb fragment of 3′ untranslated sequence unique to B-KSR1. (C) The CA4 domain and C terminus are two regions of B-KSR1 affected by alternative splicing. The amino acid sequence of these two regions in B-KSR1 is aligned to the corresponding regions of KSR1 and DmKSR1.