Today, the v-Crk cellular homologs (c-Crk) CrkI and CrkII, together with the paralog Crk-like (CrkL) protein, are categorized as adaptor proteins. CrkL was first cloned as a gene implicated in chronic myeloid leukemia (CML) [3]. The gene discussed is CRK; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.