Fig. 1.

Functional evaluation of established Z138 sub-clones. Growth of (a) wild type, cytarabine naive sensitive (Z138-CytNS) cells and (b) an in-house developed cytarabine resistant (Z138-CytR) clone in presence of different concentrations of cytarabine, was assessed by trypan blue exclusion method at indicated time-points. Each data point represents a mean value of duplicates, and error bars show SEM. The data were normalized to the 0-h time-point. c Schematic overview of the established Z138 sub-clones. Z138-CytNS cells exposed to increasing concentrations (0–0.2 μM) of cytarabine for 30 days were expanded and frozen as a cell biobank named cytarabine exposed sensitive (Z138-CytES). The frozen cell biobank was thawed and used for establishment of a cytarabine resistant (Z138-CytR21) sub-clone, by exposing cells to 0.3 μM cytarabine for a period of 21 days. Biological replicates indicated as #A-C were included. In parallel, Z138-CytES cells cultured in absence of cytarabine for indicated days were used as controls (CTR). * marks the samples used for gene expression analysis (presented in Fig. 3a). d Assessment of cell proliferation by incorporation of [methyl-14C]-thymidine indicates that Z138-CytR21 cells remain unaffected until a concentration of 50 μM cytarabine is reached, as also illustrated by (e) biological replicates. Each data point represents a mean value of triplicates, and error bars show SEM. The data, representing the 48-h time-point, are normalized to the time-point 0 h