RASSF1 and skin basal cell carcinoma: Our data showed that promoters of four genes were significantly more frequently methylated in BCC tissue versus normal skin: SHH (44/100 (40.0%) vs. 30/122 (24.6%), P = 0.016), APC (64/110 (58.2%) vs. 47/124 (37.9%), P = 0.003), SFRP5 (52/109 (47.7%) vs. 28/100 (28.0%), P = 0.004), and RASSF1A (52/112 (46.4%) vs. 39/124 (31.3%), P = 0.023.