Fig. 1. ING1 protein structure. (A) Schematic diagram of three characterized isoforms of ING1 expressed in most tissue culture cells including Hs68 fibroblasts and SNB19 cells and a recently cloned ING1-like (ING1-L) gene. All proteins contain PHD and nuclear localization signal (NLS) domains; p33^ING1b contains a PIP domain (P). Darkened regions represent isoform-unique regions and open bars represent a common exon. (B) functional regions of p33^ING1b are indicated including the PIP sequence, a partial Bromodomain and the NLS, which consists of two independent nucleolar transport sequences (Scott et al., 2001).