Results analyzed in DCIS I (more invasive) and DCIS II (less invasive) suggest that SEMA3F is induced early in DCIS, but consistent with our NRP1/NRP2 blockade analysis, only when SEMA3F and NRP1/NRP2 expression show a positive correlation, that is in DCIS I and invasive lesions, SEMA3F is fully able to signal as a proinvasive cue. Here, NRP1 is linked to ductal breast carcinoma in situ.