HTS Assay for Functional Modulators of ABCB6 Figure 1. Assay development at University of New Mexico Center for Molecular Discovery (UNMCMD). (a) Human erythroid leukemia cells (K562) expressing ABCB6 accumulate more porphyrins compared to the vector control cells as measured by flow cytometry. (b) Flow cytometric HTS of Prestwick Chemical Library (PCL). The figure depicts data from a representative PCL plate demonstrating decrease in FL2 fluorescence (representing PPIX fluorescence) mediated by verteporfin. The Y-axis displays the amount of fluorescence (FL2 log channel representing PPIX fluorescence). The X-axis displays each well. In the assays time bins were automatically drawn around the clusters by using IDLQuery software programs, each cluster corresponds to one well. The red square represents the PPIX fluorescence in untreated ABCB6 overexpressing cells while the white square represents the PPIX fluorescence in vector control cells. The arrow highlights the decrease in PPIX fluorescence of ABCB6 expressing cells in the presence of verteporfin. doi:10.1371/journal.pone.0040005.g001 PLoS ONE | www.plosone.org 5 July 2012 | Volume 7 | Issue 7 | e40005