A summary of the p300 structure-function analysis in hematopoiesis. ○ indicates that loss of the domain is similar to the p300 nullizygous phenotype. indicates that rescue of the nullizygous phenotype can be achieved in the absence of the domain. In these cases, rescue is similar to levels achieved with p300^R/− cells. • indicates that, in the absence of the domain, rescue of the nullizygous phenotype surpasses that of p300^R/− cells. The CBP column indicates rescue achieved by expressing an extra copy of CBP at the p300 locus is similar to that of p300^R/− cells.