Figure 1

Experimental design. Cells were assigned to 4 treatment groups: control (NT), chronic exposure and transformed (iAs-T), withdrawal (iAs-Rev-cells were treated for 26 days with iAs, then iAs was removed and cells grown for another 10 days) or retreatment (same as iAs-Rev but after these 10 days, cells were retreated with iAs for another 10 days). This latter experiment tests for the genes altered immediately by iAs-exposure. These groups were chosen based on observations to changes in cell morphology. Furthermore, these time points are intended to capture transcription changes due to long term arsenic exposure and withdrawal.