BCAR1

BCAR1 Full Name

breast cancer anti-estrogen resistance 1

BCAR1 Introduction

BCAR1 (breast cancer anti-estrogen resistance 1), also known as p130Cas, is a cytoplasmic scaffold/adaptor protein encoded by the BCAR1 gene and a member of the Cas family of signaling proteins. Rather than functioning as an enzyme or transcription factor, BCAR1 coordinates multiple protein–protein interactions within focal adhesions and growth-factor signaling complexes, making it an important molecular hub for translating extracellular cues into changes in cell behavior. Its modular structure enables interactions with Src-family kinases, Crk proteins, and other signaling partners, while phosphorylation of its substrate domain facilitates downstream signaling. For researchers studying cancer signaling, the key challenge is therefore not simply measuring BCAR1 expression, but understanding how its phosphorylation and protein interactions connect adhesion, growth-factor signaling, cytoskeletal remodeling, proliferation, and cell survival.

BCAR1 has a particularly important role in regulating cell adhesion, migration, and cytoskeletal dynamics. Src-dependent phosphorylation of BCAR1 creates docking sites for adaptor proteins such as Crk, enabling formation of signaling complexes that can activate RAC1 and promote actin remodeling, lamellipodia or pseudopodia formation, focal-adhesion turnover, and directional cell migration. BCAR1 also integrates signals from receptor tyrosine kinases and integrin-associated complexes, allowing cells to adapt their motility and survival programs to changes in the extracellular environment. Experimental studies further indicate that Bcar1/p130Cas is required for normal tissue development, including ventricular development and neural crest cell remodeling during cardiac outflow tract formation, highlighting that BCAR1 is not merely a cancer-associated marker but a physiologically important regulator of cell remodeling and tissue homeostasis.

In disease biology, BCAR1 is best characterized for its association with tumor progression and therapeutic resistance, particularly in breast cancer. Elevated or hyperactivated p130Cas/BCAR1 signaling has been associated with aggressive cellular phenotypes, increased proliferation and invasion, and resistance to endocrine therapy in estrogen receptor-positive breast cancer, including tamoxifen resistance. In HER2/ErbB2-positive breast cancer, BCAR1 can participate in signaling complexes that enhance receptor stability and downstream survival signaling, contributing to reduced responsiveness to HER2-targeted treatment. Its abnormal activity has also been investigated in other malignancies, including lung, prostate, and hepatocellular cancers, where its ability to couple growth-factor signaling with cytoskeletal remodeling may support tumor-cell plasticity and invasion. Consequently, BCAR1/p130Cas is a useful target for studies focused on breast cancer drug resistance, tumor-cell migration, focal-adhesion signaling, and mechanisms linking aberrant adaptor-protein signaling with cancer progression.

Alternate Names for BCAR1

BCAR1; breast cancer anti-estrogen resistance 1; CAS; CAS1; CASS1; CRKAS; P130Cas; breast cancer anti-estrogen resistance protein 1; Crk-associated substrate p130Cas; Cas scaffolding protein family member 1;

• 1.Centonze G, et al.; p130Cas/BCAR1 and p140Cap/SRCIN1 Adaptors: The Yin Yang in Breast Cancer? Front Cell Dev Biol. 2021, 9:729093.
  2.Farhadi P, Park T. The p130Cas-Crk/CrkL Axis: A Therapeutic Target for Invasive Cancers Unveiled by Collaboration Among p130Cas, Crk, and CrkL. Int J Mol Sci. 2025, 26(9):4017.