PBA inhibits cancer cell chemotaxis but BA does not. DU-145, PC-3, RWPE-1, ZR-75-1 and MCF-10A cells were assayed for chemotactic migration in the presence of indicated concentrations of Boric Acid (BA) or Phenol Boric Acid (PBA). Migration assays were performed on fibronectin coated filters with 10% FBS in the lower chambers as a chemoattractant. As a positive control, cells were plated on fibronectin coated filters in the presence of serum containing medium, without BA or PBA (Untreated). For a negative control, cells were plated on filters coated with fibronectin in the presence of serum containing medium (Blotto), or they were plated on fibronectin coated filters in medium lacking serum (Serum Free). A single asterisk (*) signifies that serum induces a significant increase in migration compared to negative controls. A double asterisk (**) indicates a significant increase in migration compared to untreated cells. Results expressed as mean ± SEM, n = 8 for each of three replicates.