βArr1 regulates the self-renewal of SP cell.

(A) H1650, H1975 and A549 cells were transfected with siRNA against βArr1 and βArr2. Frequency of SP cells was compared with non-targeting control siRNA transfected cells. SP cells are enclosed within the area demarcated in pink. Bar diagrams represent the fold difference in frequency in siRNA transfected cells in respective cell lines. (B) SP frequency was analyzed and represented for A549 cells ectopically expressing rat-βArr1 or GFP and shRNA against βArr1 or non-targeting control shRNA. (C) Real-time PCR and (D) western-blot analysis for ABCG2 expression was performed for these stable cell lines. (E, F, G) A549 cells stably expressing shRNA against βArr1 and non-targeting shRNA were plated for self-renewal assay. (E) Phase contrast microscopy images of the spheres in presence or absence of drugs are presented. (F, G) Average number and size of the spheres generated per well from 1000 cells is plotted (mean±SD).