LIF and cancer: In this second phase, the major molecular checkpoints might be factors able to confer to cancer cells implantation properties in primary local niches and angiogenesis for vascularization, such as ID1, ID3, leukemia inhibitory factor and its receptor (LIF/LIFr), IL-6/IL-6r, IL-10, gp130, Janus kinase (JAK), signal transducer and activator of transcription 3 (STAT3), HSP70, and HLA-G factors (Figure 2).