The low levels of PARP1 in p190+ CML, however, indicate that the presence of the p190 isoform alone is not enough to dictate high PARP1 expression, although the use of PARPis has already been demonstrated to have cytotoxic effect over BCR::ABL1 positive CML in vivo, even though PARP1 levels were not quantified [83]. This evidence concerns the gene BCR and chronic myelogenous leukemia, BCR-ABL1 positive.