A method for treating metastatic tumor cells of a subject is disclosed. The method comprises administrating to the subject an antisense molecule comprising a nucleotide sequence which is complementary to an RNA sequence of a protease activated receptor (PAR) protein, or an antibody molecule capable of binding to a PAR protein. A method is also described for the treatment of disorders involving the implantation of a placenta in a female subject comprising administrating to the subject the antisense molecule. Also disclosed is the antisense molecule and a pharmaceutical composition comprising it.