ROR1 and breast cancer: Other more unusual targets that showed quite promising results when targeted by CAR-NK cells are ROR1 (receptor tyrosine kinase-like orphan receptor 1) in recurrent neuroblastoma [134]; EphA2 (ephrin type-A receptor 2) in paediatric sarcomas, including rhabdomyosarcoma, Ewing sarcoma, and osteosarcoma [227]; and CD44v6 [90] and HER3 in breast cancer cells [228].