ROR1 and breast cancer: Moreover, stimulation of ROR1 with Wnt5a increased the migratory potential of tumor cells compared to the ROR1 negative cells [26] and similar observations were made on solid cancers, like chemo resistant breast cancer where ROR1 inhibition triggered p53 activity and ABC family of ATP-dependent drug efflux pumps via MAPK/ERK pathway [63, 94–98].