GRPs were highly enriched for gene expression of stemness, IGF1, and IGF1R.

<p><b>A.</b> Quantitative RT-PCR was performed with primers specific for CD133, Oct4, Sox2, Nanog, CXCR4, and ALDH1A1, which are stemness genes in PC9 or HCC827 parental cells and GRPs. <b>B.</b> Quantitative RT-PCR was performed with primers specific for IGF1 and IGF1R in PC9 or HCC827 parental cells and GRPs. Data were normalized to actin expression. *p<0.01, **p<0.001, ***p<0.0001.