To address how intratumoral heterogeneity affects anti-cancer drug responses, we profiled transcriptomes of single cancer cells originating from lung adenocarcinoma patient-derived xenograft (PDX) tumors. Overall design: We performed single-cell RNA sequencing (scRNA-Seq) together with bulk sequencing by applying Smart-Seq protocol (RamskÃ¶ld et al., Nat Biotechnol 2012). Enrichment of cancer cells in PDX from primary tumor (LC-PT-45: bulk RNA-Seq, n=1) was identified by histopathological examination and genomic signatures. Tumor cell-enriched PDX cells (LC-PT-45: scRNA-Seq, n=34; bulk RNA-Seq, n=9) were analyzed, and additional batch (LC-Pt-45-Re: scRNA-Seq, n=43; bulk RNA-Seq, n=7) was obtained to check comparable results. H358 human lung cancer cells (scRNA-Seq, n=50; bulk RNA-Seq, n=1) were used as cell line controls. Another lung cancer PDX case (LC-MBT-15: scRNA-Seq, n=49; bulk RNA-Seq, n=7) was prepared to validate our analytical strategy applied in the LC-PT-45 case.