S1P1 protein expression in hen and human tissue. S1P1 immunoreactions are similar in hen and human ovaries and ovarian tumors. Three bands at 47, 72, 108 kDa were observed. The band at 47 kDa was faint, while bands at 72 and 108 kDa were consistently present in all tissues but vary in intensity. The 47 kD band was not significantly enhanced using a membrane enriched (18,000 × g pellet) fraction. The pattern of immunoreactive bands was identical in the positive control recommended by the manufacturer (rat brain) and in hen brain and spleen. The bands were absent in control incubations in which the primary antibody was pre-adsorbed with a blocking peptide or in which the primary antibody was omitted.