PML and chronic myelogenous leukemia, BCR-ABL1 positive: The role of shelterin proteins in alternative lengthening of telomeres in chronic myeloid leukemia has not been studied in detail up to now, therefore we have decided to analyze co-localization of alternative lengthening of telomeres-associated promyelocytic leukemia (PML) nuclear bodies (APBs) with TRF2 commonly used as a marker of ALT.