We found that Plac1 ablation induced a lower Foxp3 ratio (p = 0.0083), whereas Plac1 expression induced an increase in the Foxp3+ cell ratio (p = 0.0154) and in Plac1+ tumor cells, PVR knockdown using siRNA induced a decrease in the Foxp3+ cell ratio (Plac1‐NC: p = 0.0047, Plac1‐VEC: p = 0.0193, Plac1‐OE: p = 0.0069) (Figure 6J,K). Here, PVR is linked to neoplasm.