Increasing evidence supports a role for PKCα in growth arrest and tumor suppression in the
intestinal epithelium. In contrast, the Id1 transcriptional repressor has pro-proliferative and
tumorigenic properties in this tissue. Here, we identify Id1 as a novel target of PKCα
signaling. Using a highly specific antibody and a combined morphological/biochemical
approach, we establish that Id1 is a nuclear protein restricted to proliferating intestinal crypt
cells. A relationship between PKCα and Id1 was supported by the demonstration that (a) …