Ang II receptor expression in wild-type MSF and PAN02 cells was determined by real-time PCR and expressed as threshold cycle (Ct) value. The 18S ribosomal RNA was used as an internal standard. The Ct value indicates the fractional cycle number at which the amount of amplified target reaches a fixed threshold. Cells were cultured in either serum-containing or serum-free medium for two days, total RNA was extracted, and the receptor expression was determined. The values represent the average of triplicate determinations. Serum-free culture is known to increase AT2 expression in cultured cells .