PCM1 and squamous cell carcinoma: In HPC cell lines (HPCM1 and HPCM2; both squamous cell carcinoma), we observed significant decreases in CD271 expression following transfection with small-interfering (si)RNA targeting RELA (Fig. 2A,B, and Supplemental Fig. 1), with similar results observed in HSC3 cells (tongue squamous cell carcinoma).