Female Balb/c mice were injected with 7 × 103 4T1 cells, s.c., into the mammary fat pad, at eight weeks of age. The mean tumor diameter (A) in WT (■) and Tslpr−/− (▲) mice was calculated as follows: diameter = •(l × w), where l=length and w=width. The mean tumor diameters were compared at each time point using a Student’s t test (n=8 mice/group). Asterisks indicate significant differences in the means. P values are as follows: day 27, p<0.05; day 30, p<0.03; day 35, p<0.02; day 38, p<0.05; and day 40 p<0.05. p.i: post-injection