ATR and chronic myelogenous leukemia, BCR-ABL1 positive: Given that both K562 and MEG01 are TP53-deficient CML cell lines, inhibition of CCND1 expression by miR-342-5p did lead to ATR-chk1 inhibition with ATM-chk2 activation and subsequent cell apoptosis (Fig. 5D-F) [69, 70].