S1PR1 and breast cancer: IL22R1 and S1PR1 transcripts were detectable at only low levels in low metastatic breast cancer cell lines (MCF-7, T47D, MDA-MB453, and SKBR3) but showed robustly increased levels in the highly metastatic breast cancer cell lines (HCC1954, MDA-MB231, and MDA-MB157) as determined by qPCR (Figure 2A).