Phosphorylated Crkl is one of main tyrosyl-phosphoproteins present in peripheral blood cells of CML patients, where it functions as a nuclear adaptor and transcriptional activator in BCR-ABL expressing cells (Nichols et al., 1994; Rhodes et al., 2000). The gene discussed is CRKL; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.