CSF1 and cancer: Finally, analysis of 40 patient ascites samples collected at surgery showed that nearly all samples had detectable M-CSF levels as measured by ELISA, and nearly half (19/40) had levels within the range of patients 3, 9, and 18 indicating that many ovarian cancer PDX cancer cells may express levels of M-CSF capable of stimulating myeloid differentiation (Supplementary Fig. S4).