ROR1 and breast cancer: To determine the specificity and toxicity of the ROR1-IT on cancer cells, we screened a panel breast cancer lines including ROR1-negative HMLE breast epithelial cells, HER2+ BT-474 and AU-565, and MDA-MB-436 cells, as well as ROR1+ MDA-MB-436 and Hs578T cells (Figure 3c).