The NB4 cell line was initially isolated from a patient with acute promyelocytic leukemia (APL-M3), so this cell line most closely resembles promyelocytes. Much like promyelocytes they are capable of differentiation to neutrophils and monocytes, however I have looked into their exome to compare it to primary promyelocytes. All this being said to my knowledge HL-60 cells (APL-promyelocytic cell) are the closest transformed cell line to NB4. NB4 and HL-60 cells are canonically used together in differentiation studies throughout the literature. Hope this helps.

Thank you Bayan for your suggestion.