PIP has the ability to bind immunoglobulin G (IgG), IgG-Fc, CD4-T cell receptor suggesting a wide range of immunological functions.

[11][12] PIP can bind different species of bacteria showing highest affinity to streptococci thus playing a role in non-immune defense of the body against pathogenic bacterial strains.

[18] PIP gene expression in breast cancer lines was associated with decreased cell proliferation and invasiveness and an increase of the apoptotic pathway.

[22] In molecular apocrine breast cancer (ER-/AR+) there is a positive feedback loop between androgen receptor and extracellular signal-regulated kinase (ERK) via CREB1 which can be inhibited by anti-androgens.

[23] In ER+ breast cancer, particularly those with very high level of ER expression, PIP appears to play an important role in proliferation and invasion as well as acquired resistance to tamoxifen.