Expressed, wild-type p53 in primary AML blasts exists in several acidic isoforms not seen in resting normal cells. (A) Expression of wild-type p53 was detected at high levels in AML blast samples. However, the acidity and expression level of p53 isoforms was variable among AML patients, such that the 2D pattern of p53 created a signature that distinguished AML patients from one another. (B) In contrast, full-length wild-type p53 was expressed at low levels (53-kDa band) and with a consistent 2D pattern in PBMCs from healthy donors.