DDR2 and neoplasm: (D) Primary tumor growth rate in MMTV-PyMT (WT) (n = 18 mice) or FSP1cre; Ddr2fl/fl; MMTV-PyMT (Ddr2-/- FSP1cre) (n = 10 mice) as represented by time in weeks to end stage (single tumor 2 cm in largest dimension).